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Home Books Schwartz's Principles of Surgery, 10e
Chapter 39: Pediatric Surgery
David J. Hackam; Tracy Grikscheit; Kasper Wang; Jeffrey S. Upperman; Henri R. Ford
Hackam DJ, Grikscheit T, Wang K, Upperman JS, Ford HR. Hackam D.J., & Grikscheit T, & Wang K, & Upperman J.S., & Ford H.R. Hackam, David J., et al.Pediatric Surgery. In: Brunicardi F, Andersen DK, Billiar TR, Dunn DL, Hunter JG, Matthews JB, Pollock RE. Brunicardi F, & Andersen D.K., & Billiar T.R., & Dunn D.L., & Hunter J.G., & Matthews J.B., & Pollock R.E.(Eds.),Eds. F. Charles Brunicardi, et al.eds. Schwartz's Principles of Surgery, 10e. McGraw Hill; 2015. Accessed January 27, 2023. https://accesssurgery.mhmedical.com/content.aspx?bookid=980&sectionid=59610881
Hackam DJ, Grikscheit T, Wang K, Upperman JS, Ford HR. Hackam D.J., & Grikscheit T, & Wang K, & Upperman J.S., & Ford H.R. Hackam, David J., et al. (2015). Pediatric surgery. Brunicardi F, Andersen DK, Billiar TR, Dunn DL, Hunter JG, Matthews JB, Pollock RE. Brunicardi F, & Andersen D.K., & Billiar T.R., & Dunn D.L., & Hunter J.G., & Matthews J.B., & Pollock R.E.(Eds.),Eds. F. Charles Brunicardi, et al. Schwartz's Principles of Surgery, 10e. McGraw Hill. https://accesssurgery.mhmedical.com/content.aspx?bookid=980&sectionid=59610881
Hackam DJ, Grikscheit T, Wang K, Upperman JS, Ford HR. Hackam D.J., & Grikscheit T, & Wang K, & Upperman J.S., & Ford H.R. Hackam, David J., et al. "Pediatric Surgery." Schwartz's Principles of Surgery, 10e Brunicardi F, Andersen DK, Billiar TR, Dunn DL, Hunter JG, Matthews JB, Pollock RE. Brunicardi F, & Andersen D.K., & Billiar T.R., & Dunn D.L., & Hunter J.G., & Matthews J.B., & Pollock R.E.(Eds.),Eds. F. Charles Brunicardi, et al. McGraw Hill, 2015, https://accesssurgery.mhmedical.com/content.aspx?bookid=980&sectionid=59610881.
PEDIATRIC SURGICAL THEMES: PITFALLS AND PEARLS
DEFORMITIES OF THE ABDOMINAL WALL
PEDIATRIC MALIGNANCY
TRAUMA IN CHILDREN
FETAL INTERVENTION
In infants with Bochdalek-type congenital diaphragmatic hernia, the severity of pulmonary hypoplasia and the resultant pulmonary hypertension are key determinants of survival. Barotrauma and hypoxia should be avoided.
During initial management of an infant with esophageal atresia and distal tracheoesophageal fistula, every effort should be made to avoid distending the gastrointestinal tract, especially when using mechanical ventilation. The patient should be evaluated for components of the VACTERRL (vertebral, anorectal, cardiac, tracheoesophageal, renal, radial limb) anomalies. Timing and extent of surgery are dictated by the stability of the patient.
Although malrotation with midgut volvulus occurs most commonly within the first few weeks of life, it should always be considered in the differential diagnosis in a child with bilious emesis. Volvulus is a surgical emergency; therefore, in a critically ill child, prompt surgical intervention should not be delayed for any reason.
When evaluating a newborn infant for vomiting, it is critical to distinguish between proximal and distal causes of intestinal obstruction using both prenatal and postnatal history, physical examination, and abdominal radiographs.
Risk factors for necrotizing enterocolitis (NEC) include prematurity, formula feeding, bacterial infection, and intestinal ischemia. Critical to the management of infants with advanced (Bell stage III) or perforated NEC is timely and adequate source control of peritoneal contamination. Early sequelae of NEC include perforation, sepsis, and death. Later sequelae include short bowel syndrome and stricture.
In patients with intestinal obstruction secondary to Hirschsprung's disease, a leveling ostomy or endorectal pull-through should be performed using ganglionated bowel, proximal to the transition zone between ganglionic and aganglionic intestine.
Prognosis of infants with biliary atresia is directly related to age at diagnosis and timing of portoenterostomy. Infants with advanced age at the time of diagnosis or infants who fail to demonstrate evidence of bile drainage after portoenterostomy usually require liver transplantation.
Infants with omphaloceles have greater associated morbidity and mortality than infants with gastroschisis due to a higher incidence of congenital anomalies and pulmonary hypoplasia. Gastroschisis can be associated with intestinal atresia, but not with other congenital anomalies. An intact omphalocele can be repaired electively, whereas gastroschisis requires urgent intervention to protect the exposed intestine.
Prognosis for children with Wilms' tumor is defined by the stage of disease at the time of diagnosis and the histologic type (favorable vs. unfavorable). Preoperative chemotherapy is indicated for bilateral involvement, a solitary kidney, or tumor in the inferior vena cava above the hepatic veins. Gross tumor rupture during surgery automatically changes the stage to 3 (at a minimum).
Injury is the leading cause of death in children older than 1 year of age. Blunt mechanisms account for the majority of pediatric injuries. The central nervous system is the most commonly injured organ system and the leading cause of death in injured children.
In his 1953 classic textbook entitled The Surgery of Infancy and Childhood, Dr. Robert E. Gross summarized the essential challenge of pediatric surgery: "Those who daily operate upon adults, even with the greatest of skill, are sometimes appalled – or certainly are not at their best – when called upon to operate upon and care for a tiny patient. Something more than diminutive instruments or scaled-down operative manipulations are necessary to do the job in a suitable manner." To this day, surgical residents and other trainees often approach the pediatric surgical patient with the same mix of fear, trepidation, and anxiety. Importantly, these same trainees typically complete their pediatric surgical rotations with a profound respect for the resilience of young children to undergo complex operations, and with an appreciation for the precision required from their caregivers, both in the operating room and during the perioperative period. Over the decades, the specialty of pediatric surgery has evolved considerably to encompass not only the care of the smallest patients with surgical disorders, who may require in utero interventions in certain circumstances, but also the care of older infants, children, adolescents, and young adults. Similarly, our understanding of the pathophysiology of the diseases that pediatric surgeons face has evolved to the point that some pediatric surgical diseases are now understood at the level of molecular or cellular signaling pathways. Pediatric surgery provides the opportunity to intervene positively in a wide array of diseases and to exert a long-lasting impact on the lives of children and their grateful parents. The scope of diseases encountered in the standard practice of pediatric surgery is immense and includes anomalies of the head and neck, thoracic, gastrointestinal, and genitourinary areas. This chapter is not designed to cover the entire spectrum of diseases a pediatric surgeon is expected to master; rather, it presents a synopsis of a handful of pediatric surgical conditions that a practicing general surgeon is likely to encounter over the course of his or her career.
This chapter focuses on the unique considerations regarding the diagnosis and management of surgical diseases in the pediatric population. Many surgical trainees approach the surgical care of children with some degree of fear and trepidation. As any pediatric caregiver will attest to, the surgical management of infants and children requires delicate, careful, and professional interactions with their parents. The stress that the parents of sick children experience in the hospital setting can, at times, be overwhelming. It is due, in part, to the uncertainty regarding a particular prognosis, the feeling of helplessness that evolves when one is unable to care for one's own child, and in certain cases, the guilt or remorse that one feels for not seeking medical care earlier or for consenting to a particular procedure. Management of the sick child and his or her family requires not only a certain set of skills, but also a unique knowledge base. This section is included to summarize some important general principles in accomplishing this task.
Children are not little adults, but they are little people. In practical terms, this often-heard refrain implies that children have unique fluid, electrolyte, and medication needs. Thus, the dosage of medications and the administration of intravenous fluids should be based on their weight. The corollary of this point is that infants and young children are extremely sensitive to perturbations in their normal physiology, and as such may easily experience fluid overload or dehydration.
Sick children whisper before they shout. Children with surgical diseases can deteriorate very quickly. But before they deteriorate, they often manifest subtle physical findings. These findings—referred to as "whispers"—may include signs such as tachycardia, bradycardia, hypothermia, fever, recurrent emesis, or feeding intolerance. Meticulous attention to these subtle findings may unmask the development of potentially serious, life-threatening physiologic disturbances.
Always listen to the mother and the father. Surgical diseases in children can be very difficult to diagnose because children are often minimally communicative and information that they communicate may be confusing, conflicting, or both. In all cases, it is wise to listen to the child's parents, who have closely observed their child and know him or her best. Most importantly, the child's parents know with certainty whether or not the child is sick despite not always knowing the precise diagnosis.
Children suffer pain after surgery. Timely and adequate pain management must accompany surgical interventions.
Pediatric tissue must be handled delicately and with profound respect.
In managing the pediatric surgical patient, an understanding of fluid and electrolyte balance is critical, as the margin between dehydration and fluid overload is rather small. This is particularly true in infants, who have little reserve when ill. Failure to pay meticulous attention to their hydration status can result in significant fluid overload or dehydration. Several surgical diagnoses such as gastroschisis or short-gut syndrome are characterized by a predisposition to fluid loss. Others require judicious restoration of intravascular volume in order to prevent cardiac failure, as is the case in patients with congenital diaphragmatic hernia and associated pulmonary hypertension. The infant's physiologic day is approximately 8 hours in duration. Accordingly, careful assessment of the individual patient's fluid balance, including fluid intake and output for the previous 8 hours, is essential to prevent dehydration or fluid overload. Clinical signs of dehydration include tachycardia, decreased urine output, reduced skin turgor, a depressed fontanelle, absent tears, lethargy, and poor feeding. Fluid overload is often manifested by the onset of new oxygen requirement, respiratory distress, tachypnea, and tachycardia. The physical assessment of the fluid status of each child must include a complete head-to-toe evaluation, with emphasis on determining whether perturbations in normal physiology are present.
At 12 weeks' gestation, the total body water of a fetus is approximately 94 cc/kg. By the time the fetus reaches full term, the total body water has decreased to approximately 80 cc/kg. Total body water drops an additional 5% within the first week of life, and by 1 year of life, total body water approaches adult levels, around 60 to 65 cc/kg. Parallel to the drop in total body water is the reduction in extracellular fluid. These changes are accelerated in the preterm infant who may face additional fluid losses due to coexisting congenital anomalies or surgery. Normal daily maintenance fluids for most children can be estimated using the following formula: 100 mL/kg for the first 10 kg, plus 50 mL/kg for 11 to 20 kg, plus 25 mL/kg for each additional kilogram of body weight thereafter. Because intravenous (IV) fluid orders are written as milliliters per hour, this can be conveniently converted as follows: 4 mL/kg/h up to 10 kg, add 2 mL/kg/h for 11 to 20 kg, and add 1 mL/kg/h for each additional kilogram of body weight thereafter. For example, a 26-kg child has an estimated maintenance fluid requirement of (10 × 4) + (10 × 2) + (6 × 1) = 66 mL/h in the absence of massive fluid losses or shock. A newborn infant with gastroschisis will manifest significant evaporative losses from the exposed bowel such that fluid requirements may range from 150 to 180 cc/kg/d. Precise management of a neonate's fluid status requires an understanding of changes in the glomerular filtration rate (GFR) and tubular function of the kidney. The term newborn's GFR is approximately 21 mL/min/1.73 m2 compared to 70 mL/min/1.73 m2 in an adult. Within the first 2 weeks of life, GFR increases to approximately 60, and by 2 years of age, it is essentially at adult levels. The capacity to concentrate urine is very limited in preterm and term infants. Compared with an adult who can concentrate urine to 1200 mOsm/kg, infants can concentrate urine at best to 600 mOsm/kg. While infants are capable of secreting antidiuretic hormone (ADH), the aquaporin water channel–mediated osmotic water permeability of the infant's collecting tubules is severely limited compared with that of adults, leading to insensitivity to ADH.
Sodium requirements range from 2 mEq/kg/d in term infants up to 5 mEq/kg/d in critically ill preterm infants as a consequence of salt wasting. Potassium requirements are on the order of 1 to 2 mEq/kg/d. Calcium and magnesium supplementation of IV fluids is essential to prevent laryngospasm, dysrhythmias, and tetany.
Acid-Base Equilibrium
Acute metabolic acidosis usually implies inadequate tissue perfusion and is a serious disorder in children. Potentially life-threatening causes that are specific for the pediatric population must be sought; they include intestinal ischemia from necrotizing enterocolitis (in the neonate), midgut volvulus, or incarcerated hernia. Other causes include chronic bicarbonate loss from the gastrointestinal tract or acid accumulation as in chronic renal failure. Respiratory acidosis implies hypoventilation, the cause of which should be apparent. Treatment of acute metabolic acidosis should be aimed at restoring tissue perfusion by addressing the underlying abnormality first. For severe metabolic acidemia where the serum pH is less than 7.25, sodium bicarbonate should be administered using the following guideline: base deficit × weight in kilograms × 0.5 (in newborns). The last factor in the equation should be 0.4 for smaller children and 0.3 for older children. The dose should be diluted to a concentration of 0.5 mEq/mL because full-strength sodium bicarbonate is hyperosmolar. One half of the corrective dose is given, and the serum pH is measured again. During cardiopulmonary resuscitation (CPR), one half of the corrective dose can be given as an IV bolus and the other half given slowly via IV.
Respiratory alkalosis is usually caused by hyperventilation, which is readily correctable. Metabolic alkalosis most commonly implies gastric acid loss, as in the child with pyloric stenosis, or aggressive diuretic therapy. In the child with gastric fluid loss, IV fluids of 5% dextrose, 0.5% normal saline, and 20 mEq KCl/L usually correct the alkalosis.
Blood Volume and Blood Replacement
Criteria for blood transfusion in infants and children remain poorly defined. The decision to transfuse a critically ill pediatric patient may depend on a number of clinical features that include the patient's age, primary diagnosis, the presence of ongoing bleeding, coagulopathy, hypoxia, hemodynamic compromise, lactic acidosis, cyanotic heart disease, and overall severity of illness. A recent survey of transfusion practices among pediatric intensivists showed that the baseline hemoglobin levels that would prompt them to recommend packed red blood cell (PRBC) transfusion ranged from 7 to 13 g/dL. Patients with cyanotic heart disease are often transfused to higher hemoglobin values, although the threshold for transfusion in this population remains to be defined. To decrease the need for transfusion, other strategies have been considered. Studies in both critically ill adults and neonates have shown that administration of erythropoietin decreases PRBC transfusion requirements. In general terms, there is a trend toward an avoidance of the use of PRBC products whenever possible, as current studies suggest that lower hemoglobin concentrations are well tolerated by many groups of patients, whereas administration of PRBCs may have unintended negative consequences. In addition, there is increasing evidence that PRBC transfusion may have adverse effects on the host immune system, in both children and adults. These effects are poorly understood but may be due to red blood cell (RBC) storage or factors that are particular to the individual RBC donor.
A useful guideline for estimating blood volume for the newborn infant is approximately 80 mL/kg of body weight. When PRBCs are required, the transfusion requirement is usually administered in 10-mL/kg increments, which is roughly equivalent to a 500-mL transfusion for a 70-kg adult. The following formula may be used to determine the volume (mL) of PRBCs to be transfused:
(Target hematocrit – Current hematocrit) ë weight (kg) ë 80/65(65 represents the estimated hematocrit of a unit of PRBC)
In the child, coagulation deficiencies rapidly may assume clinical significance after extensive blood transfusion. It is advisable to have fresh frozen plasma and platelets available if more than 30 mL/kg have been transfused. Plasma is given in a dose of 10 to 20 mL/kg, and platelets are given in a dose of 1 unit/5 kg. Each unit of platelets consists of 40 to 60 mL of fluid (plasma plus platelets). Following transfusion of PRBCs to neonates with tenuous fluid balance, a single dose of a diuretic (such as furosemide 1 mg/kg) may help to facilitate excretion of the extra fluid load. Many clinicians prefer to administer fresh products to minimize the deleterious effects of red cell storage.
The nutritional requirements of the surgical neonate must be met in order for the child to grow and to heal surgical wounds. If inadequate protein and carbohydrate calories are given, the child may not only fail to recover from surgery, but may also exhibit growth failure and impaired development of the central nervous system. In general terms, the adequacy of growth must be assessed frequently, by determining both total body weight and head circumference. Neonates who are particularly predisposed to protein-calorie malnutrition include those with gastroschisis, intestinal atresia, or intestinal insufficiency from other causes, such as necrotizing enterocolitis. The protein and caloric requirements for the surgical neonate are shown in Table 39-1.
Table 39-1Nutritional requirements for the pediatric surgical patient
Table 39-1 Nutritional requirements for the pediatric surgical patient
CALORIES (kcal/kg/d)
PROTEIN (g/kg/d)
0–6 months 100–120 2
6 months–1 year 100 1.5
1–3 years 100 1.2
4–6 years 90 1
7–10 years 70 1
11–14 years 55 1
Nutrition can be provided via either the enteral or parenteral route. Whenever possible, the enteral route is preferred because it not only promotes the growth and function of the gastrointestinal system, but also ensures that the infant learns how to feed. There are various enteral feeding preparations available; these are outlined in Table 39-2. The choice of formula is based on the individual clinical state of the child. Pediatric surgeons are often faced with situations where oral feeding is not possible. This problem can be seen in the extremely premature infant who has not yet developed feeding skills or in the infant with concomitant craniofacial anomalies that impair sucking, for example. In these instances, enteral feeds can be administered either via a nasojejunal or a gastrostomy tube.
Table 39-2Formulas for pediatric surgical neonates
Table 39-2 Formulas for pediatric surgical neonates
kcal/mL
PROTEIN (g/mL)
FAT (g/mL)
CARBOHYDRATE (g/mL)
Human milk 0.67 0.011 0.04 0.07
Milk-based formula
Enfamil 20 0.67 0.015 0.038 0.069
Similac 20 0.67 0.015 0.036 0.072
Soy-based formula
Prosobee 0.67 0.02 0.036 0.07
Isomil 0.67 0.018 0.037 0.068
Special formula
Pregestimil 0.67 0.019 0.028 0.091
Alimentum 0.67 0.019 0.038 0.068
Enfamil Premature 0.80 0.024 0.041 0.089
When the gastrointestinal tract cannot be used because of mechanical, ischemic, inflammatory, or functional disorders, parenteral alimentation must be given. Prolonged parenteral nutrition is delivered via a central venous catheter. Peripheral IV alimentation can be given, using less concentrated but greater volumes of solutions. Long-term parenteral nutrition should include supplemental copper, zinc, and iron to prevent the development of trace metal deficiencies. A major complication of long-term total parenteral nutrition (TPN) is the development of parenteral nutrition-associated cholestasis, which can eventually progress to liver failure. To prevent this major complication, concomitant enteral feedings should be instituted and the gastrointestinal tract should be used as soon as possible. When proximal stomas are in place, gastrointestinal continuity should be restored as soon as possible. Where intestinal insufficiency is associated with dilation of the small intestine, tapering or intestinal lengthening procedures may be beneficial. Other strategies to minimize the development of TPN-related liver disease include meticulous catheter care to avoid infection, which increases cholestatic symptoms, aggressive treatment of any infection, and early cycling of parenteral nutrition in older children who can tolerate not receiving continuous dextrose solution for a limited period. Preliminary evidence suggests the possibility that substituting omega-3 fish oil lipid emulsion in parenteral nutrition for the standard soybean-based emulsions may prevent the development of TPN-related cholestasis and reverse the effects of established liver disease.
Venous Access
Obtaining reliable vascular access in an infant or child is an important task that often becomes the responsibility of the pediatric surgeon. The goal should always be to place the catheter in the least invasive, least risky, and least painful manner, and in a location that is most accessible and allows for use of the catheter without complications for as long as it is needed. In infants, central venous access may be established using a cutdown approach, either in the antecubital fossa, external jugular vein, facial vein, or proximal saphenous vein. If the internal jugular vein is used, care is taken to prevent venous occlusion. In infants over 3 kg and in older children, percutaneous access of the subclavian, internal jugular, or femoral veins is possible in most cases, and central access is achieved using the Seldinger technique. The catheters are tunneled to an exit site separate from the venotomy site. Where available, peripherally inserted central catheter (PICC) lines may be placed, typically via the antecubital fossa. Regardless of whether the catheter is placed by a cutdown approach or percutaneously, a chest x-ray to confirm central location of the catheter tip and to exclude the presence of a pneumothorax or hemothorax is mandatory. When discussing the placement of central venous catheters with parents, it is important to note that the complication rate for central venous lines in children can be high. The incidence of catheter-related sepsis or infection approaches 10% in many series, although recent reports show a lower incidence. Superior or inferior vena caval occlusion is a significant risk after the placement of multiple lines, particularly in the smallest premature patients.
Careful regulation of the ambient environment of infants and children is crucial, as these patients are extremely thermolabile. Premature infants are particularly susceptible to changes in environmental temperature. Because they are unable to shiver and lack stores of fat, their potential for thermogenesis is impaired. The innate inability to regulate temperature is compounded by the administration of anesthetic and paralyzing agents. Since these patients lack adaptive mechanisms to cope with the environment, the environmental temperature must be regulated. Attention to heat conservation during transport of the infant to and from the operating room is essential. Transport systems incorporating heating units are necessary for premature infants. In the operating room, the infant is kept warm by the use of overhead heating lamps, a heating blanket, warming the room as well as inspired gases, and coverage of the extremities and head with occlusive materials. During abdominal surgery, extreme care is taken to avoid wet and cold drapes. All fluids used to irrigate the chest or abdomen must be warmed to body temperature. Laparoscopic approaches for abdominal operations may result in more stable thermoregulation due to decreased heat loss from the smaller wound size. Constant monitoring of the child's temperature is critical in a lengthy procedure, and the surgeon should continuously communicate with the anesthesiologist regarding the temperature of the patient. The development of hypothermia in infants and children can result in cardiac arrhythmias or coagulopathy. These potentially life-threatening complications can be avoided by careful attention to thermoregulation.
All children, including neonates, experience pain. Therefore, careful recognition and management of pediatric pain represents an important component of the perioperative management of all pediatric surgical patients. There is a range of pain management options that can improve the child's well-being, as well as the parents' sense of comfort. The use of a pacifier, which may be dipped in sucrose, has been shown to decrease crying time and neonatal pain scores after minor procedures. For situations where more pain is expected, IV narcotic agents should be used. Morphine and fentanyl have an acceptable safety margin and can be administered judiciously to neonates and children. A randomized clinical trial involving neonates on ventilators showed that the use of a morphine infusion decreased the incidence of intraventricular hemorrhage by 50%. Additional analgesic modalities include the use of topical anesthetic ointment (EMLA cream), regional anesthesia such as caudal blocks for hernias, and epidural or incisional catheter infusions (On-Q™) for large abdominal or thoracic incisions. In surgical neonates who have received large concentrations of narcotics over a prolonged period, transient physical dependence should not only be expected, but anticipated. When narcotics are discontinued, symptoms of narcotic withdrawal may develop, including irritability, restlessness, and episodes of hypertension and tachycardia. Early recognition of these signs is essential, as is timely treatment using naloxone and other agents. In the postoperative period, patient-controlled analgesia is another excellent method of pain control. By ensuring that the pediatric surgical patient has adequate analgesia, the surgeon ensures that the patient receives the most humane and thorough treatment and provides important reassurance to all other members of the healthcare team and to the family that pain control is a very high priority.
The management of neck masses in children is determined by their location and the length of time that they have been present. Neck lesions are found either in the midline or lateral compartments. Midline masses include thyroglossal duct remnants, thyroid masses, thymic cysts, or dermoid cysts. Lateral lesions include branchial cleft remnants, cystic hygromas, vascular malformations, salivary gland tumors, torticollis, and lipoblastoma (a rare benign mesenchymal tumor of embryonal fat occurring in infants and young children). Enlarged lymph nodes and rare malignancies such as rhabdomyosarcoma can occur either in the midline or laterally.
The most common cause of a neck mass in a child is an enlarged lymph node, which typically can be found laterally or in the midline. The patient is usually referred to the pediatric surgeon for evaluation after the mass has been present for several weeks. A detailed history and physical examination often helps determine the likely etiology of the lymph node and the need for excisional biopsy. Enlarged tender lymph nodes are usually the result of a bacterial infection (Staphylococcus or Streptococcus). Treatment of the primary cause (e.g., otitis media or pharyngitis) with antibiotics often is all that is necessary. However, when the involved nodes become fluctuant, incision and drainage are indicated. In many North American institutions, there has been an increasing prevalence of methicillin-resistant Staphylococcus aureus infection of the skin and soft tissues, leading to increased staphylococcal lymphadenitis in children. More chronic forms of lymphadenitis, including infections with atypical mycobacteria, as well as cat-scratch fever, are diagnosed based on serologic findings or excisional biopsy. The lymphadenopathy associated with infectious mononucleosis can be diagnosed based on serology. When the neck nodes are firm, fixed, and others are also present in the axillae or groin, or the history suggests lymphoma, excisional biopsy is indicated. In these cases, it is essential to obtain a chest radiograph to look for the presence of a mediastinal mass. Significant mediastinal load portends cardiorespiratory collapse due to loss of venous return and compression of the tracheobronchial tree with general anesthesia. Accordingly, such biopsies should be done under local anesthesia.
Thyroglossal Duct Remnants
Pathology and Clinical Manifestations
The thyroid gland buds off the foregut diverticulum at the base of the tongue in the region of the future foramen cecum at 3 weeks of embryonic life. As the fetal neck develops, the thyroid tissue becomes more anterior and caudad until it rests in its normal position. The "descent" of the thyroid is intimately connected with the development of the hyoid bone. Residual thyroid tissue left behind during the migration may persist and subsequently present in the midline of the neck as a thyroglossal duct cyst. The mass is most commonly appreciated in the 2- to 4-year-old child when the baby fat disappears and irregularities in the neck become more readily apparent. Usually the cyst is encountered in the midline at or below the level of the hyoid bone, and moves up and down with swallowing or with protrusion of the tongue. Occasionally it presents as an intrathyroidal mass. Most thyroglossal duct cysts are asymptomatic. If the duct retains its connection with the pharynx, infection may occur, and the resulting abscess will necessitate incision and drainage, occasionally resulting in a salivary fistula. Submental lymphadenopathy and midline dermoid cysts can be confused with a thyroglossal duct cyst. Rarely, midline ectopic thyroid tissue masquerades as a thyroglossal duct cyst and may represent the patient's only thyroid tissue. Therefore, if there is any question regarding the diagnosis or if the thyroid gland cannot be palpated in its normal anatomic position, it is advisable to obtain a nuclear scan to confirm the presence of a normal thyroid gland. Although rarely the case in children, in adults the thyroglossal duct may contain thyroid tissue that can undergo malignant degeneration. The presence of malignancy in a thyroglossal cyst should be suspected when the cyst grows rapidly or when the ultrasound demonstrates a complex anechoic pattern or the presence of calcification.
If the cyst presents with an abscess, treatment should first consist of drainage and antibiotics. Following resolution of the inflammation, resection of the cyst in continuity with the central portion of the hyoid bone and the tract connecting to the pharynx in addition to ligation at the foramen cecum (the Sistrunk operation) is curative in over 90% of patients. Lesser operations result in unacceptably high recurrence rates, and recurrence is more frequent following infection. According to a recent review, factors predictive of recurrence included more than two infections prior to surgery, age under 2 years, and inadequate initial operation.
Branchial Cleft Anomalies
Paired branchial clefts and arches develop early in the fourth gestational week. The first cleft and the first, second, third, and fourth pouches give rise to adult organs. The embryologic communication between the pharynx and the external surface may persist as a fistula. A fistula is seen most commonly with the second branchial cleft, which normally disappears, and extends from the anterior border of the sternocleidomastoid muscle superiorly, inward through the bifurcation of the carotid artery, and enters the posterolateral pharynx just below the tonsillar fossa. In contrast, a third branchial cleft fistula passes posterior to the carotid bifurcation. The branchial cleft remnants may contain small pieces of cartilage and cysts, but internal fistulas are rare. A second branchial cleft sinus is suspected when clear fluid is noted draining from the external opening of the tract at the anterior border of the lower third of the sternomastoid muscle. Rarely, branchial cleft anomalies occur in association with biliary atresia and congenital cardiac anomalies, an association that is referred to as Goldenhar's complex.
Complete excision of the cyst and sinus tract is necessary for cure. Dissection of the sinus tract is facilitated with passage of a fine lacrimal duct probe through the external opening into the tract and using it as a guide for dissection. Injection of a small amount of methylene blue dye into the tract also may be useful. A series of two or sometimes three small transverse incisions in a "stepladder" fashion is preferred to a long oblique incision in the neck, which is cosmetically undesirable. Branchial cleft cysts can present as abscesses. In these cases, initial treatment includes incision and drainage with a course of antibiotics to cover Staphylococcus and Streptococcus species, followed by excision of the cyst after the infection resolves.
Lymphatic Malformation
Etiology and Pathology
Lymphatic malformation (previously known as cystic hygroma or lymphangioma) occurs as a result of sequestration or obstruction of developing lymph vessels in approximately 1 in 12,000 births. Although the lesion can occur anywhere, the most common sites are in the posterior triangle of the neck, axilla, groin, and mediastinum. The cysts are lined by endothelium and filled with lymph. Occasionally unilocular cysts occur, but more often, there are multiple cysts "infiltrating" the surrounding structures and distorting the local anatomy. A particularly troublesome variant of lymphatic malformation is one that involves the tongue, floor of the mouth, and structures deep in the neck. Adjacent connective tissue may show extensive lymphocytic infiltration. The mass may be apparent at birth or may appear and enlarge rapidly in the early weeks or months of life as lymph accumulates; most present by age 2 years (Fig. 39-1A). Extension of the lesion into the axilla or mediastinum occurs about 10% of the time and can be demonstrated preoperatively by chest x-ray, ultrasound (US), or computed tomography (CT) scan. Occasionally lymphatic malformations contain nests of vascular tissue. These poorly supported vessels may bleed and produce rapid enlargement and discoloration of the mass. Infection within the cysts, usually caused by Streptococcus or Staphylococcus, may occur. In the neck, this can cause rapid enlargement, which may result in airway compromise. Rarely, it may be necessary to carry out percutaneous aspiration of a cyst to relieve respiratory distress.
Figure 39-1.
A. Left cervical lymphatic malformation in a 2-day-old baby. B. Intraoperative photograph showing a vessel loop around the spinal accessory nerve.
The diagnosis of lymphatic malformation by prenatal US, before 30 weeks' gestation, has detected a "hidden mortality" as well as a high incidence of associated anomalies, including abnormal karyotypes and hydrops fetalis. Occasionally, very large lesions can cause obstruction of the fetal airway. Such obstruction can result in the development of polyhydramnios by impairing the ability of the fetus to swallow amniotic fluid. In these circumstances, the airway is usually markedly distorted, which can result in immediate airway obstruction unless the airway is secured at the time of delivery. Orotracheal intubation or emergency tracheostomy while the infant remains attached to the placenta, the so-called EXIT procedure (ex utero intrapartum treatment), may be necessary to secure the airway.
The modern management of most lymphatic malformations includes the combination of surgical excision and image-guided sclerotherapy. The initial treatment typically involves surgery in an attempt to safely remove all gross disease without damaging vital structures. Total removal of all gross disease may not be possible because of the extent of the lymphatic malformation and its proximity to, and intimate relationship with, adjacent nerves, muscles, and blood vessels (Fig. 39-1B). Radical ablative surgery is not indicated for this lesion. A combined sclerotherapy/resectional approach is particularly useful for large lymphatic malformations and those that extend to the base of the tongue or the floor of the mouth. Conservative excision and unroofing of the cysts is advised along with sclerotherapy or repeated partial excision for any residual lymphatic malformation if necessary, preserving all adjacent crucial structures. Postoperative wound drainage is important and is best accomplished by closed-suction technique. Nevertheless, fluid may accumulate beneath the surgically created flaps, requiring multiple needle aspirations.
The presence of a lateral neck mass in infancy in association with rotation of the head toward the opposite side of the mass indicates the presence of congenital torticollis. This lesion results from fibrosis of the sternocleidomastoid muscle. The mass may be palpated in the affected muscle in approximately two thirds of cases. Histologically, the lesion is characterized by the deposition of collagen and fibroblasts around atrophied muscle cells. In the vast majority of cases, physical therapy based on passive stretching of the affected muscle is of benefit. Rarely, surgical transection of the sternocleidomastoid may be indicated.
Congenital Diaphragmatic Hernia (Bochdalek)
The septum transversum extends to divide the pleural and coelomic cavities during fetal development. This precursor of the diaphragm normally completes separation of these two cavities at the posterolateral aspects of this mesenchymally derived structure. The most common variant of a congenital diaphragmatic hernia is a posterolateral defect, also known as a Bochdalek hernia. Diaphragmatic defects allow abdominal viscera to fill the chest cavity. The abdominal cavity is small and underdeveloped and remains scaphoid after birth. Both lungs are hypoplastic, with decreased bronchial and pulmonary artery branching. Lung weight, lung volume, and DNA content are also decreased, and these findings are more striking on the ipsilateral side. This anomaly is encountered more commonly on the left (80%–90%). Linkage analyses have recently implicated genetic mutations in syndromic variants of congenital diaphragmatic hernias. In many instances, there is a surfactant deficiency, which compounds the degree of respiratory insufficiency. Amniocentesis with karyotype may identify chromosomal defects, especially trisomy 18 and 21. Associated anomalies, once thought to be uncommon, were identified in 65 of 166 patients in one study, predominantly of the heart, followed by abdominal wall defects, chromosomal changes, and other defects. Prenatal ultrasonography is successful in making the diagnosis of congenital diaphragmatic hernia (CDH) as early as 15 weeks' gestation, and early antenatal diagnosis is associated with worse outcomes. US findings include herniated abdominal viscera in the chest, which may also look like a mass or lung anomaly, changes in liver position, and mediastinal shift away from the herniated viscera (Fig. 39-2). Accurate prenatal prediction of outcome for fetuses who have CDH is very difficult. One index of severity for patients with left CDH is the lung-to-head ratio (LHR), which is the product of the length and the width of the right lung at the level of the cardiac atria divided by the head circumference (all measurements in millimeters). An LHR value of less than 1.0 is associated with a very poor prognosis, whereas an LHR greater than 1.4 predicts a more favorable outcome. The utility of the LHR in predicting outcome in patients with CDH has recently been questioned, due to the tremendous interobserver variability in calculating this ratio for a particular patient, as well as the lack of reliable measures to determine postnatal disease severity.
Prenatal ultrasound of a fetus with a congenital diaphragmatic hernia. Arrows point to the location of the diaphragm. Arrow head points to the stomach, which is in the thoracic cavity.
Following delivery, the diagnosis of CDH is made by chest x-ray (Fig. 39-3). The differential diagnosis includes bronchopulmonary foregut malformations, in which the intrathoracic loops of bowel may be confused for lung or foregut pathology. The vast majority of infants with CDH develop immediate respiratory distress, which is due to the combined effects of three factors. First, the air-filled bowel in the chest compresses the mobile mediastinum, which shifts to the opposite side of the chest, compromising air exchange in the contralateral lung. Second, pulmonary hypertension develops. This phenomenon results in persistent fetal circulation, with resultant decreased pulmonary perfusion and impaired gas exchange. Finally, the lung on the affected side is often hypoplastic, such that it is essentially nonfunctional. Varying degrees of pulmonary hypoplasia on the opposite side may compound these effects. The second and third factors are thought to be the most important. Neonates with CDH are usually in respiratory distress requiring ventilation and intensive care, and the overall mortality in most series is around 50%.
Chest x-ray showing a left congenital diaphragmatic hernia.
CDH care has improved considerably through effective use of improved methods of ventilation and timely cannulation for extracorporeal membrane oxygenation (ECMO). Many infants are symptomatic at birth due to hypoxia, hypercarbia, and metabolic acidosis. Prompt cardiorespiratory stabilization is mandatory. It is noteworthy that in some infants, the first 24 to 48 hours after birth are often characterized by a period of relative stability with high levels of PaO2 and relatively good perfusion. This has been termed the "honeymoon period" and is often followed by progressive cardiorespiratory deterioration. In the past, correction of the hernia was believed to be a surgical emergency, and patients underwent surgery shortly after birth. It is now accepted that the presence of persistent pulmonary hypertension that results in right-to-left shunting across the patent foramen ovale or the ductus arteriosus and the degree of pulmonary hypoplasia are the leading causes of cardiorespiratory insufficiency. Current management therefore is directed toward managing the pulmonary hypertension and minimizing barotrauma while optimizing oxygen delivery. To achieve this goal, infants are placed on mechanical ventilation using relatively low or "gentle" settings that prevent overinflation of the noninvolved lung. Levels of PaCO2 in the rangeof 50 to 60 mmHg or higher are accepted as long as the pH remains ≥ 7.25. If these objectives cannot be achieved using conventional ventilation, high-frequency oscillatory ventilation (HFOV) may be used to avoid the injurious effects of conventional tidal volume ventilation. Echocardiography will assess the degree of pulmonary hypertension and identify the presence of any coexisting cardiac anomaly. Intensive care unit goals include minimal sedation, meticulous attention to endotracheal tube secretions, and gradual changes to ventilator settings to avoid inducing pulmonary hypertension via hypoxia. To minimize the degree of pulmonary hypertension, inhaled nitric oxide may be administered and, in some patients, improves pulmonary perfusion. Nitric oxide is administered into the ventilation circuit and is used in concentrations up to 40 parts per million. Correction of acidosis using bicarbonate solution may minimize the degree of pulmonary hypertension. As the degree of pulmonary hypertension becomes hemodynamically significant, right-sided heart failure develops and systemic perfusion is impaired. Administration of excess IV fluid will compound the degree of cardiac failure and lead to marked peripheral edema. Inotropic support using epinephrine, dopamine, and milrinone alone or in combination may be useful in optimizing cardiac contractility and maintaining mean arterial pressure.
Infants with CDH who remain severely hypoxic despite maximal ventilatory care may be candidates for treatment of their respiratory failure by ECMO, with access via venovenous (VV) or venoarterial (VA) routes. VV bypass is established with a single cannula through the right internal jugular vein, with blood removed from and infused into the right atrium by separate ports. VA bypass provides additional cardiac support, whereas VV bypass requires a well-functioning heart and relies on the lungs for some oxygenation as well. In VA ECMO, the right atrium is cannulated by means of the internal jugular vein and the aortic arch through the right common carotid artery. As much of the cardiac output is directed through the membrane oxygenator as is necessary to provide oxygenated blood to the infant and remove carbon dioxide. The infant is maintained on bypass until the pulmonary hypertension is resolved and lung function, as measured by compliance and the ability to oxygenate and ventilate, is improved. This is usually seen within 7 to 10 days, but in some infants, it may take up to several weeks to occur. Complications associated with ECMO increase after 14 days and include cannula malposition, bleeding in multiple locations, and infection. The use of ECMO is associated with significant risk. Because patients require systemic anticoagulation, bleeding complications are the most significant. They may occur intracranially or at the site of cannula insertion and can be life threatening. Systemic sepsis is a significant problem and may necessitate decannulation. Criteria for placing infants on ECMO include the presence of normal cardiac anatomy by echocardiography, the absence of fatal chromosome anomalies, and the expectation that the infant would die without ECMO. Traditionally, a threshold of weight greater than 2 kg and gestational age greater than 34 weeks has been applied, although success has been achieved at weights as low as 1.8 kg. Upon decannulation, some centers repair the carotid artery. In instances in which the child is cannulated for a brief period (5 days or less) this may be feasible. A recent study failed to show any benefit from repairing the carotid artery, although this finding remains to be studied further.
A strategy that does not involve the use of ECMO, but instead emphasizes the use of permissive hypercapnia and the avoidance of barotrauma, may provide equal overall outcome in patients with CDH. This likely reflects the fact that mortality is related to the degree of pulmonary hypoplasia and the presence of congenital anomalies, neither of which are correctable by ECMO.
The timing of diaphragmatic hernia repair is still approached by various routes in major centers, particularly when the infant is on ECMO. In patients who are not on ECMO, repair should be performed once the hemodynamic status has been optimized. In neonates who are on ECMO, some surgeons perform early repair on bypass; others wait until the infant's lungs are improved and the pulmonary hypertension has subsided, repair the diaphragm, and discontinue bypass within hours of surgery. Still others repair the diaphragm only after the infant is off bypass. Operative repair of the diaphragmatic hernia may be accomplished by either an abdominal or transthoracic approach and can be performed either via open or minimally invasive techniques. Through a subcostal incision, the abdominal viscera are withdrawn from the chest, exposing the defect in the diaphragm. Care must be taken when reducing the spleen and liver, as bleeding from these structures can be fatal. The anterior margin is often apparent, while the posterior muscular rim is attenuated. If the infant is heparinized on bypass, minimal dissection of the muscular margins is performed. Electrocautery is used liberally to minimize postoperative bleeding. Most infants who require ECMO support prior to hernia repair have large defects, often lacking the medial and posterior margins. About three fourths of infants repaired on bypass require prosthetic material to patch the defect, suturing it to the diaphragmatic remnant or around ribs or costal cartilages for the large defects. If there is adequate muscle for closure, a single layer of nonabsorbable horizontal mattress sutures, pledgeted or not, closes the defect. Just before the repair is complete, a chest tube may be positioned in the thoracic cavity but is not mandatory. Patients repaired on ECMO are at risk for developing a hemothorax, which can significantly impair ventilation. Anatomic closure of the abdominal wall may be impossible after reduction of the viscera. Occasionally a prosthetic patch or acellular material may be sutured to the fascia to facilitate closure. The patch can be removed at a later time, and the ventral hernia can be closed at that time or subsequently. In patients who are deemed to be candidates for a minimally invasive approach (stable patients, >2 kg, no pulmonary hypertension), a thoracoscopic repair may be safely performed, although concerns have been raised about possible effects of the longer operative time for thoracoscopic repair and higher recurrence rates. If the diaphragm has been repaired on ECMO, weaning and decannulation are accomplished as soon as possible. All infants are ventilated postoperatively to maintain preductal arterial oxygenation of 80 to 100 Torr. Very slow weaning from the ventilator is necessary to avoid recurrent pulmonary hypertension.
Congenital Lobar Emphysema
Congenital lobar emphysema (CLE) is a condition manifested during the first few months of life as a progressive hyperexpansion of one or more lobes of the lung. It can be life-threatening in the newborn period if extensive lung tissue is involved, but in the older infant and in cases in which the lesion is less severely distended, it causes less respiratory distress. Air entering during inspiration is trapped in the lobe; on expiration, the lobe cannot deflate and progressively overexpands, causing atelectasis of the adjacent lobe or lobes. This hyperexpansion eventually shifts the mediastinum to the opposite side and compromises the other lung. CLE usually occurs in the upper lobes of the lung (left greater than right), followed next in frequency by the right middle lobe, but it also can occur in the lower lobes. It is caused by intrinsic bronchial obstruction from poor bronchial cartilage development or extrinsic compression. Approximately 14% of children with this condition have cardiac defects, with an enlarged left atrium or a major vessel causing compression of the ipsilateral bronchus.
Symptoms range from mild respiratory distress to full-fledged respiratory failure with tachypnea, dyspnea, cough, and late cyanosis. These symptoms may be stationary, or they may progress rapidly or result in recurrent pneumonia. Occasionally, infants with CLE present with failure to thrive, which likely reflects the increased work associated with the overexpanded lung. A hyperexpanded hemithorax on the ipsilateral side is pathognomonic for CLE. Diagnosis is typically confirmed by chest x-ray, which shows a hyperlucent affected lobe with adjacent lobar compression and atelectasis. The mediastinum may be shifted as a consequence of mass effect to the contralateral side causing compression and atelectasis of the contralateral lung (Fig. 39-4). Although chest radiograph is usually sufficient, it is sometimes important to obtain a CT scan of the chest to clearly establish the diagnosis of CLE. This should be done only in the stable patient. Unless foreign body or mucus plugging is suspected as a cause of hyperinflation, bronchoscopy is not advisable because it can lead to more air trapping and cause life-threatening respiratory distress in a stable infant. Treatment is resection of the affected lobe, which can be safely performed using either an open or thoracoscopic approach. Unless symptoms necessitate earlier surgery, resection can usually be performed after the infant is several months of age. The prognosis is excellent.
Congenital lobar emphysema of the left upper lobe in a 2-week-old boy. Mediastinal shift is present.
Bronchopulmonary Foregut Malformations
Bronchopulmonary foregut malformations include foregut duplication cysts, congenital pulmonary airway malformations, and pulmonary sequestrations as discussed below.
Congenital Pulmonary Airway Malformations
Previously denoted as congenital cystic adenomatoid malformation (CCAM), congenital pulmonary airway malformation (CPAM) exhibits cystic proliferation of the terminal airway, producing cysts lined by mucus-producing respiratory epithelium, and elastic tissue in the cyst walls without cartilage formation. There may be a single cyst with a wall of connective tissue containing smooth muscle. Cysts may be large and multiple (type I), smaller and more numerous (type II), or resemble fetal lung without macroscopic cysts (type III). CPAMs frequently occur in the left lower lobe. However, this lesion can occur in any location and may occur in more than one lobe on more than one side, although this is rare. Clinical symptoms range from none to severe respiratory failure at birth. Over time, these malformations can be subject to repeated infections and produce fever and cough in older infants and children. The diagnosis is usually confirmed by CT for surgical planning and characteristic features that might delineate other bronchopulmonary foregut malformations (Fig. 39-5). Prenatal US may suggest the diagnosis. Resection is curative and may need to be performed urgently in the infant with severe respiratory distress. Long term, there is a risk of malignant degeneration in unresected CPAMs, but this risk occurs over decades and has not been fully defined. As a result, resection of the affected lobe is usually performed (Fig. 39-6).
Computed tomography scan of the chest showing a congenital pulmonary airway malformation involving the left lower lobe.
Intraoperative photograph showing left lower lobe congenital pulmonary airway malformation seen in Fig. 39-5.
Pulmonary Sequestration
Pulmonary sequestration is uncommon and consists of a mass of lung tissue, usually in the left lower chest, occurring without the usual connections to the pulmonary artery or tracheobronchial tree, yet with a systemic blood supply from the aorta. There are two kinds of sequestration. Extralobar sequestration is usually a small area of nonaerated lung separated from the main lung mass, with a systemic blood supply, located immediately above the left diaphragm. It is commonly found in cases of CDH. Intralobar sequestration more commonly occurs within the parenchyma of the left lower lobe but can occur on the right. There is no major connection to the tracheobronchial tree, but a secondary connection may be established, perhaps through infection or via adjacent intrapulmonary shunts. The blood supply frequently originates from the aorta below the diaphragm; multiple vessels may be present (Fig. 39-7). Venous drainage of both types can be systemic or pulmonary. The cause of sequestration is unknown but most probably involves an abnormal budding of the developing lung that picks up a systemic blood supply and never becomes connected with the bronchus or pulmonary vessels. Sequestrations may, in some cases, exhibit mixed pathology with components consistent with CPAMs. Extralobar sequestration is asymptomatic and is usually discovered incidentally on chest x-ray. If the diagnosis can be confirmed (e.g., by CT scan), resection is not necessary. Diagnosis of intralobar sequestration may be made prenatally and confirmed on postnatal CT scan. Alternatively, the diagnosis of intralobar sequestration may be established after repeated infections manifested by cough, fever, and consolidation in the posterior basal segment of the left lower lobe. Increasingly the diagnosis is being made in the early months of life by US, and color Doppler often can be helpful in delineating the systemic arterial supply. Removal of the entire left lower lobe is usually necessary since the diagnosis often is made late after multiple infections. Occasionally segmental resection of the sequestered part of the lung can be performed using an open or, ideally, a thoracoscopic approach. If an open approach is used, it is important to open the chest through a low intercostal space (sixth or seventh) to gain access to the vascular attachments to the aorta. These attachments may insert into the aorta below the diaphragm; in these cases division of the vessels as they traverse the thoracic cavity is essential. Prognosis is generally excellent. However, failure to obtain adequate control of these vessels may result in their retraction into the abdomen and result in uncontrollable hemorrhage. It is also possible to perform a combined thoracoscopic and open approach, wherein the vessels are clipped and divided thoracoscopically and then the lesion is safely removed through a limited thoracotomy.
Arteriogram showing large systemic artery supply to intralobar sequestration of the left lower lobe.
Bronchogenic Cyst
Bronchogenic cysts are duplication cysts originating from the airway, regardless of the identity of the epithelial lining. They can occur anywhere along the respiratory tract and can present at any age, although typically they present after accumulation of intraluminal contents, and not within the newborn period. Histologically, they are hamartomatous and usually consist of a single cyst lined with an epithelium; the mesenchyme contains cartilage and smooth muscle. They are probably embryonic rests of foregut origin that have been pinched off from the main portion of the developing tracheobronchial tree and are closely associated in causation with other foregut duplication cysts such as those arising from the esophagus. Bronchogenic cysts may be seen on prenatal US but are discovered most often incidentally on postnatal chest x-ray. Although they may be completely asymptomatic, bronchogenic cysts may produce symptoms, usually compressive in nature, depending on the anatomic location and size, which increase over time if there is no egress of accumulating luminal contents. In the paratracheal region of the neck, they can produce airway compression and respiratory distress. In the lung parenchyma, they may become infected and present with fever and cough. In addition they may cause obstruction of the bronchial lumen with distal atelectasis and infection, or they may cause mediastinal compression. Rarely, rupture of the cyst can occur. Chest x-ray usually shows a dense mass, and CT scan or magnetic resonance imaging (MRI) delineates the precise anatomic location of the lesion. Treatment consists of resection of the cyst, which may need to be undertaken in emergency circumstances for airway or cardiac compression. Resection can be performed either as an open procedure or, more commonly, using a thoracoscopic approach. If resection of a common wall will result in injury to the airway, resection of the inner epithelial cyst lining after marsupialization is acceptable.
Bronchiectasis is an abnormal and irreversible dilatation of the bronchi and bronchioles associated with chronic suppurative disease of the airways. Usually patients have an underlying congenital pulmonary anomaly, cystic fibrosis, or immunologic deficiency. Bronchiectasis can also result from chronic infection secondary to a neglected bronchial foreign body. The symptoms include a chronic cough, often productive of purulent secretions, recurrent pulmonary infection, and hemoptysis. The diagnosis is suggested by a chest x-ray that shows increased bronchovascular markings in the affected lobe. Chest CT delineates bronchiectasis with excellent resolution. The preferred treatment for bronchiectasis is medical, consisting of antibiotics, postural drainage, and bronchodilator therapy, since many children with the disease show signs of airflow obstruction and bronchial hyperresponsiveness. Lobectomy or segmental resection is indicated for localized disease that has not responded appropriately to medical therapy. In severe cases, lung transplantation may be required to replace the terminally damaged, septic lung.
Foreign Bodies
The inherent curiosity of children and their innate propensity to place new objects into their mouths to fully explore them place them at great risk for aspiration. Aspirated objects can be found either in the airway or in the esophagus; in both cases, the results can be life-threatening.
Airway Ingestion
Aspiration of foreign bodies most commonly occurs in the toddler age group. Peanuts are the most common object that is aspirated, although other materials (popcorn, for instance) may also be involved. A solid foreign body often will cause air trapping, with hyperlucency of the affected lobe or lung seen especially on expiration. Oil from the peanut is very irritating and may cause pneumonia. Delay in diagnosis can lead to atelectasis and infection. The most common anatomic location for a foreign body is the right main stem bronchus or the right lower lobe. The child usually will cough or choke while eating but may then become asymptomatic. Total respiratory obstruction with tracheal foreign body may occur; however, respiratory distress is usually mild if present at all. A unilateral wheeze is often heard on auscultation. This wheeze often leads to an inappropriate diagnosis of "asthma" and may delay the correct diagnosis for some time. Chest x-ray will show a radiopaque foreign body, but in the case of nuts, seeds, or plastic toy parts, the only clue may be hyperexpansion of the affected lobe on an expiratory film or fluoroscopy. Bronchoscopy confirms the diagnosis and allows removal of the foreign body. It can be a very simple procedure, or it may be extremely difficult, especially with a smooth foreign body that cannot be grasped easily or one that has been retained for some time. The rigid bronchoscope should be used in all cases, and utilization of the optical forceps facilitates grasping the inhaled object. Epinephrine may be injected into the mucosa when the object has been present for a long period of time, which minimizes bleeding. Bronchiectasis may be seen as an extremely late phenomenon after repeated infections of the poorly aerated lung and may require partial or total resection of the affected lobe. The differential diagnosis of a bronchial foreign body includes an intraluminal tumor (i.e., carcinoid, hemangioma, or neurofibroma).
Foreign Bodies and Esophageal Injury
The most common foreign body in the esophagus is a coin, followed by small toy parts. Toddlers are most commonly affected. The coin is retained in the esophagus at one of three locations: the cricopharyngeus, the area of the aortic arch, or the gastroesophageal junction—all areas of normal anatomic narrowing. Symptoms are variable depending on the anatomic position of the foreign body and the degree of obstruction. There is often a relatively asymptomatic period after ingestion. The initial symptoms are gastrointestinal and include dysphagia, drooling, and dehydration. The longer the foreign body remains in the esophagus with oral secretions unable to transit the esophagus, the greater the incidence of respiratory symptoms including cough, stridor, and wheezing. These findings may be interpreted as signs of upper respiratory infections. Objects that are present for a long period, particularly in children who have underlying neurologic impairment, may manifest as chronic dysphagia. The chest x-ray is diagnostic in the case of a coin. A contrast swallow, or preferably an esophagoscopy, may be required for nonradiopaque foreign bodies. Coins lodged within the upper esophagus for less than 24 hours may be removed using Magill forceps during direct laryngoscopy. For all other situations, the treatment is by esophagoscopy, rigid or flexible, and removal of the foreign body. In the case of sharp foreign bodies such as open safety pins, extreme care is required on extraction to avoid injury to the esophagus. Rarely, esophagotomy is required for removal, particularly of sharp objects. Diligent follow-up is required after removal of foreign bodies, especially batteries, which can cause strictures, and sharp objects, which can injure the underlying esophagus. In the case of a retained battery, this case should be handled as a surgical emergency, as the negative pole of the battery directly damages the surrounding tissue, and tracheoesophageal fistula, aortic exsanguination, and mediastinitis have all been described after local tissue necrosis at the site where the battery has lodged.
Esophageal Atresia and Tracheoesophageal Fistula
Esophageal atresia (EA) with tracheoesophageal fistula (TEF) is one of the most gratifying pediatric surgical conditions to treat. In the not-so-distant past, nearly all infants born with EA and TEF died. In 1939, Ladd and Leven performed the first successful repair by ligating the fistula, placing a gastrostomy, and reconstructing the esophagus at a later time. Subsequently, Dr. Cameron Haight in Ann Arbor, Michigan, performed the first successful primary anastomosis for EA, which remains the current approach for treatment of this condition. Despite the fact that there are several common varieties of this anomaly and the underlying cause remains obscure, a careful approach consisting of meticulous perioperative care and attention to the technical detail of the operation can result in an excellent prognosis in most cases.
Anatomic Varieties
The five major varieties of EA and TEF are shown in Fig. 39-8. The most commonly seen variety is EA with distal TEF (type C), which occurs in approximately 85% of the cases in most series. The next most frequent type is pure EA (type A), occurring in 8% to 10% of patients, followed by TEF without EA (type E). This occurs in 8% of cases and is also referred to as an H-type fistula, based on the anatomic similarity to that letter (Fig. 39-9). EA with fistula between both proximal and distal ends of the esophagus and trachea (type D) is seen in approximately 2% of cases, and type B, EA with TEF between proximal esophagus and trachea, is seen in approximately 1% of all cases.
The five varieties of esophageal atresia and tracheoesophageal fistula. A. Isolated esophageal atresia. B. Esophageal atresia with tracheoesophageal fistula between proximal segment of esophagus and trachea. C. Esophageal atresia with tracheoesophageal fistula between distal esophagus and trachea. D. Esophageal atresia with fistula between both proximal and distal ends of esophagus and trachea. E. Tracheoesophageal fistula without esophageal atresia (H-type fistula).
Barium esophagram showing H-type tracheoesophageal fistula (arrow).
Etiology and Pathologic Presentation
The esophagus and trachea share a common embryologic origin. At approximately 4 weeks' gestation, a diverticulum forms off the anterior aspect of the proximal foregut in the region of the primitive pharynx. This diverticulum extends caudally with progressive formation of the laryngotracheal groove, thus creating a separate trachea and esophagus. Successful development of these structures is the consequence of extremely intricate interplay of growth and transcription factors necessary for rostral-caudal and anterior-posterior specification. The variations in clinically observed EA and TEF that must result in failure of successful formation of these structures are depicted in Fig. 39-8. Although definitive genetic mutations have been difficult to identify in isolated EA-TEF, mutations in N-myc, Sox2, and CHD7 have been characterized in syndromic EA-TEF with associated anomalies.
Other congenital anomalies commonly occur in association with EA-TEF. For instance, VACTERRL syndrome is associated with vertebral anomalies (absent vertebrae or hemivertebrae) and anorectal anomalies (imperforate anus), cardiac defects, tracheoesophageal fistula, renal anomalies (renal agenesis, renal anomalies), and radial limb hyperplasia. In nearly 20% of the infants born with EA, some variant of congenital heart disease occurs.
Clinical Presentation of Infants with Esophageal Atresia and Tracheoesophageal Fistula
The anatomic variant of infants with EA-TEF predicts the clinical presentation. When the esophagus ends either as a blind pouch or as a fistula into the trachea (as in types A, B, C, or D), infants present with excessive drooling, followed by chocking or coughing immediately after feeding is initiated as a result of aspiration through the fistula tract. As the neonate coughs and cries, air is transmitted through the fistula into the stomach, resulting in abdominal distention. As the abdomen distends, it becomes increasingly more difficult for the infant to breathe. This leads to further atelectasis and respiratory compromise. In patients with type C and D varieties, the regurgitated gastric juice passes through the fistula where it collects in the trachea and lungs and leads to a chemical pneumonitis, which further exacerbates the pulmonary difficulties. In many instances, the diagnosis is actually made by the nursing staff who attempt to feed the baby and notice the accumulation of oral secretions.
The diagnosis of EA is confirmed by the inability to pass an orogastric tube into the stomach (Fig. 39-10). The dilated upper pouch may be occasionally seen on a plain chest radiograph. If a soft feeding tube is used, the tube will coil in the upper pouch, which provides further diagnostic certainty. An important alternative diagnosis that must be considered when an orogastric tube does not enter the stomach is that of an esophageal perforation. This problem can occur in infants after traumatic insertion of a nasogastric or orogastric tube. In this instance, the perforation classically occurs at the level of the piriform sinus, and a false passage is created, which prevents the tube from entering the stomach. Whenever there is any diagnostic uncertainty, a contrast study will confirm the diagnosis of EA and occasionally document the TEF. The presence of a TEF can be demonstrated clinically by finding air in the gastrointestinal tract. This can be proven at the bedside by percussion of the abdomen and confirmed by obtaining a plain abdominal radiograph. Occasionally, a diagnosis of EA-TEF can be suspected prenatally on US evaluation. Typical features include failure to visualize the stomach and the presence of polyhydramnios. These findings reflect the absence of efficient swallowing by the fetus.
Figure 39-10.
Type C esophageal atresia with tracheoesophageal fistula. Note the catheter that is coiled in the upper pouch and the presence of gas below the diaphragm, which confirms the presence of the tracheoesophageal fistula.
In a child with EA, it is important to identify whether coexisting anomalies are present. These include cardiac defects in 38%, skeletal defects in 19%, neurologic defects in 15%, renal defects in 15%, anorectal defects in 8%, and other abnormalities in 13%. Examination of the heart and great vessels with echocardiography is important to exclude cardiac defects, as these are often the most important predictors of survival in these infants. The echocardiogram also demonstrates whether the aortic arch is left sided or right sided, which may influence the approach to surgical repair. Vertebral anomalies are assessed by plain radiography, and a spinal US is obtained if any are detected. A patent anus should be confirmed clinically. The kidneys in a newborn may be assessed clinically by palpation. An US of the abdomen will demonstrate the presence of renal anomalies, which should be suspected in the child who fails to make urine. The presence of extremity anomalies is suspected when there are missing digits and confirmed by plain radiographs of the hands, feet, forearms, and legs. Rib anomalies may also be present. These may include the presence of a thirteenth rib.
Initial Management
The initial treatment of infants with EA-TEF includes attention to the respiratory status, decompression of the upper pouch, and appropriate timing of surgery. Because the major determinant of poor survival is the presence of other severe anomalies, a search for other defects including congenital cardiac disease is undertaken in a timely fashion. The initial strategy after the diagnosis is confirmed is to place the neonate in an infant warmer with the head elevated at least 30°. A sump catheter is placed in the upper pouch on continuous suction. Both of these strategies are designed to minimize the degree of aspiration from the esophageal pouch. When saliva accumulates in the upper pouch and is aspirated into the lungs, coughing, bronchospasm, and desaturation episodes can occur, which may be minimized by ensuring the patency of the sump catheter. IV antibiotic therapy is initiated, and warmed electrolyte solution is administered. Where possible, the right upper extremity is avoided as a site to start an IV line, as this location may interfere with positioning of the patient during the surgical repair.
The timing of repair is influenced by the stability of the patient. Definitive repair of the EA-TEF is rarely a surgical emergency. If the child is hemodynamically stable and is oxygenating well, definitive repair may be performed within 1 to 2 days after birth. This allows for a careful determination of the presence of coexisting anomalies and for selection of an experienced anesthetic team.
Management of Esophageal Atresia and Tracheoesophageal Fistula in the Preterm Infant
The ventilated, premature neonate with EA-TEF and associated hyaline membrane disease represents a patient who may develop severe, progressive, cardiopulmonary dysfunction. The TEF can worsen the fragile pulmonary status as a result of recurrent aspiration through the fistula and increased abdominal distention, which impairs lung expansion. Moreover, the elevated airway pressure that is required to ventilate these patients can worsen the clinical course by forcing air through the fistula into the stomach, thereby exacerbating the degree of abdominal distention and compromising lung expansion. In this situation, the first priority is to minimize the degree of positive pressure needed to adequately ventilate the child. This can be accomplished using HFOV. If the gastric distention becomes severe, a gastrostomy tube should be placed. This procedure can be performed at the bedside under local anesthetic, if necessary. The dilated, air-filled stomach can easily be accessed through an incision in the left upper quadrant of the abdomen. Once the gastrostomy tube is placed and the abdominal pressure is relieved, the pulmonary status can paradoxically worsen. This is because the ventilated gas may pass preferentially through the fistula, which is the path of least resistance, and bypass the lungs, thereby worsening the hypoxemia. To correct this problem, the gastrostomy tube may be placed under water seal, elevated, or intermittently clamped. If these maneuvers are to no avail, ligation of the fistula may be required. This procedure can be performed in the neonatal intensive care unit if the infant is too unstable to be transported to the operating room. These interventions allow for the infant's underlying hyaline membrane disease to improve, for the pulmonary secretions to clear, and for the infant to reach a period of stability so that definitive repair can be performed.
Primary Surgical Correction
In a stable infant, definitive repair is achieved through performance of a primary esophago-esophagostomy. There are two approaches to this operation: open thoracotomy or thoracoscopy. In the open approach, the infant is brought to the operating room, intubated, and placed in the lateral decubitus position with the right side up in preparation for right posterolateral thoracotomy. If a right-sided arch was determined previously by echocardiography, consideration is given to performing the repair through the left chest, although most surgeons believe that the repair can be performed safely from the right side as well. Bronchoscopy may be performed to exclude the presence of additional, upper pouch fistulae in cases of EA (i.e., differentiation of type B, C, and D variants) and to identify a laryngotracheoesophageal cleft.
The operative technique for primary repair is as follows (Fig. 39-11). A retropleural approach is generally used, as this technique prevents widespread contamination of the thorax if a postoperative anastomotic leak occurs. The sequence of steps is as follows: (a) mobilization of the pleura to expose the structures in the posterior mediastinum; (b) division of the fistula and closure of the tracheal opening; (c) mobilization of the upper esophagus sufficiently to permit an anastomosis without tension and to determine whether a fistula is present between the upper esophagus and the trachea (forward pressure by the anesthesia staff on the sump drain in the pouch can greatly facilitate dissection at this stage of the operation; care must be taken when dissecting posteriorly to avoid violation of the lumen of the trachea and esophagus); (d) mobilization of the distal esophagus (this needs to be performed judiciously to avoid devascularization, since the blood supply to the distal esophagus is segmental from the aorta; most of the esophageal length is obtained from mobilizing the upper pouch, since the blood supply travels via the submucosa from above); (e) performing a primary esophagoesophageal anastomosis (most surgeons perform this procedure in a single layer using 5-0 sutures; if there is excess tension, the muscle of the upper pouch can be circumferentially incised without compromising blood supply to increase its length; many surgeons place a transanastomotic feeding tube in order to institute feeds in the early postoperative period); and (f) placement of a retropleural drain and closure of the incision in layers.
Primary repair of type C tracheosophageal fistula. A. Right thoracotomy incision. B. Azygos vein transected, proximal and distal esophagus demonstrated, and fistula identified. C. Tracheoesophageal fistula transected and defect in trachea closed. D. End-to-end anastomosis between proximal and distal esophagus (posterior row). E. Completed anastomosis.
When a minimally invasive approach is selected, the patient is prepared for right-sided, transthoracic thoracoscopic repair. The same steps as described earlier for the open repair are undertaken, and the magnification and superb optics that are provided by the thoracoscopic approach provide for superb visualization. Identification of the fistula is performed as a first step; this can be readily ligated and divided between thoracoscopically placed sutures. The anastomosis is performed in a single layer. The thoracoscopically performed TEF repair requires clear and ongoing communication between the operating surgeons and the anesthesiologist; visualization can be significantly reduced with sudden changes in lung inflation, potentially leading to the need to convert to an open repair. Although clear guidelines for patient selection for a thoracoscopic repair as opposed to an open repair remain lacking, reasonable selection criteria include patients over 2.5 kg who are hemodynamically stable and without comorbidities.
Postoperative Course
The postoperative management strategy of patients with EA-TEF is influenced to a great degree by the preference of the individual surgeon and the institutional culture. Many surgeons prefer not to leave the infants intubated postoperatively, to avoid the effects of positive pressure on the site of tracheal closure. However, early extubation may not be possible in babies with preoperative lung disease either from prematurity or pneumonia or when there is any vocal cord edema. When a transanastomotic tube is placed, feeds are begun slowly in the postoperative period. Some surgeons institute parenteral nutrition for several days, using a central line. The retropleural drain is assessed daily for the presence of saliva, indicating an anastomotic leak. Many surgeons obtain a contrast swallow 1 week after repair to assess the caliber of the anastomosis and to determine whether a leak is present. If there is no leak, feedings are started. The principal benefit of the thoracoscopic approach is that postoperative pain is significantly reduced, as is the requirement for postoperative narcotic analgesia.
Complications of Surgery
Anastomotic leak occurs in 10% to 15% of patients and may be seen either in the immediate postoperative period or after several days. Early leakage (i.e., within the first 24 to 48 hours) is manifested by a new pleural effusion, pneumothorax, and sepsis, and requires immediate exploration. In these circumstances, the anastomosis may be completely disrupted, possibly due to excessive tension. Revision of the anastomosis may be possible. If not, cervical esophagostomy and gastrostomy placement are required, with a subsequent procedure to re-establish esophageal continuity. Anastomotic leakage that is detected after several days usually heals without intervention, particularly if a retropleural approach is used. Under these circumstances, broad-spectrum antibiotics, pulmonary toilet, and optimization of nutrition are important. After approximately a week or so, a repeat esophagram should be performed, at which time the leakage may have resolved.
Strictures are not infrequent (10%–20%), particularly if a leak has occurred. A stricture may become apparent at any time, from the early postoperative period to months or years later. It may present as choking, gagging, or failure to thrive, but often becomes clinically apparent with the transition to eating solid food. A contrast swallow or esophagoscopy is confirmatory, and simple dilatation is usually corrective. Occasionally, repeated dilatations are required. These may be performed in a retrograde fashion, during which a silk suture is placed into the oropharynx and delivered from the esophagus through a gastrostomy tube. Tucker dilators are then tied to the suture and passed in a retrograde fashion from the gastrostomy tube and delivered out of the oropharynx. Increasing sizes are used, and the silk is replaced at the end of the procedure where it is taped to the side of the face at one end and to the gastrostomy tube at the other. Alternatively, image-guided balloon dilation over a guide wire may be performed, using intraoperative contrast radiography to determine the precise location of the stricture and to assess the immediate response to the dilation.
"Recurrent" TEF may represent a missed upper pouch fistula or a true recurrence. This may occur after an anastomotic disruption, during which the recurrent fistula may heal spontaneously. Otherwise, reoperation may be required. Recently, the use of fibrin glue has been successful in treating recurrent fistulas, although long-term follow-up is lacking.
Gastroesophageal reflux commonly occurs after repair of EA-TEF, potentially due to alterations in esophageal motility and the anatomy of the gastroesophageal junction. The clinical manifestations of such reflux are similar to those seen in other infants with primary gastroesophageal reflux disease. A loose antireflux procedure, such as a Nissen fundoplication, is used to prevent further reflux, but the child may have feeding problems after antireflux surgery as a result of the intrinsic dysmotility of the distal esophagus. The fundoplication may be safely performed laparoscopically in experienced hands, although care should be taken to ensure that the wrap is not excessively tight.
Patients with type E TEFs (also called H-type) most commonly present beyond the newborn period. Presenting symptoms include recurrent chest infections, bronchospasm, and failure to thrive. The diagnosis is suspected using barium esophagography and confirmed by endoscopic visualization of the fistula. Surgical correction is generally possible through a cervical approach with concurrent placement of a balloon catheter across the fistula and requires mobilization and division of the fistula. Outcome is usually excellent.
Patients with duodenal atresia and EA-TEF may require urgent treatment due to the presence of a closed obstruction of the stomach and proximal duodenum. In stable patients, treatment consists of repair of the esophageal anomaly and correction of the duodenal atresia if the infant is stable during surgery. If not, a staged approach should be used consisting of ligation of the fistula and placement of a gastrostomy tube. Definitive repair can then be performed at a later point in time.
Primary EA (type A) represents a challenging problem, particularly if the upper and lower ends are too far apart for an anastomosis to be created. Under these circumstances, treatment strategies include placement of a gastrostomy tube and performing serial bougienage to increase the length of the upper pouch. This occasionally allows for primary anastomosis to be performed. Occasionally, when the two ends cannot be brought safely together, esophageal replacement is required using a gastric pull-up, reverse gastric tube, or colon interposition (see below).
Various classification systems have been used to predict survival in patients with EA-TEF and to stratify treatment. A system devised by Waterston in 1962 was used to stratify neonates based on birth weight, the presence of pneumonia, and the identification of other congenital anomalies. In response to advances in neonatal care, the surgeons from the Montreal Children's Hospital proposed a new classification system. In the Montreal experience, only two characteristics independently affected survival: preoperative ventilator dependence and associated major anomalies. Pulmonary disease as defined by ventilator dependence appeared to be more accurate than pneumonia. When the two systems were compared, the Montreal system more accurately identified children at highest risk. Spitz and colleagues analyzed risk factors in infants who died with EA-TEF. Two criteria were found to be important predictors of outcome: birth weight less than 1500 g and the presence of major congenital cardiac disease. A new classification for predicting outcome in EA was therefore proposed: group I: birth weight ≥1500 g, without major cardiac disease, survival 97% (283 of 293); group II: birth weight <1500 g, or major cardiac disease, survival 59% (41 of 70); and group III: birth weight <1500 g, and major cardiac disease, survival 22% (2 of 9).
In general, surgical correction of EA-TEF leads to a satisfactory outcome with nearly normal esophageal function in most patients. Overall survival rates of greater than 90% have been achieved in patients classified as stable in all the various staging systems. Unstable infants have an increased mortality (40% to 60% survival) because of potentially fatal associated cardiac and chromosomal anomalies or prematurity. However, the use of a staged procedure also has increased survival in even these high-risk infants.
Corrosive Injury of the Esophagus
Injury to the esophagus after ingestion of corrosive substances most commonly occurs in the toddler age group. Both strong alkali and strong acids produce injury by liquefaction or coagulation necrosis, and since all corrosive agents are extremely hygroscopic, the caustic substance will cling to the esophageal epithelium. Subsequent strictures occur at the anatomic narrowed areas of the esophagus, cricopharyngeus, midesophagus, and gastroesophageal junction. A child who has swallowed an injurious substance may be symptom free but usually will be drooling and unable to swallow saliva. The injury may be restricted to the oropharynx and esophagus or may extend to include the stomach. There is no effective immediate antidote. Diagnosis is by careful physical examination of the mouth and endoscopy with a flexible or a rigid esophagoscope. It is important to endoscope only to the first level of the burn in order to avoid perforation. Early barium swallow may delineate the extent of the mucosal injury. It is important to realize that the esophagus may be burned without evidence of injury to the mouth. Although previously used routinely, steroids have not been shown to alter stricture development or modify the extent of injury. Therefore, they are no longer part of the management of caustic injuries. Antibiotics are administered during theacute period.
The extent of injury is graded endoscopically as either mild, moderate, or severe (grade I, II, or III). Circumferential esophageal injuries with necrosis have an extremely high likelihood of stricture formation. These patients should undergo placement of a gastrostomy tube once clinically stable. A string should be inserted through the esophagus either immediately or during repeat esophagoscopy several weeks later. When established strictures are present (usually 3–4 weeks), dilatation is performed. Retrograde dilatations are safest, using graduated dilators brought through the gastrostomy and advanced into the esophagus via the transesophageal string. For less severe injuries, dilatation may be attempted in antegrade fashion by either graded bougies or balloons. Management of esophageal perforation during dilation should include antibiotics, irrigation, and closed drainage of the thoracic cavity to prevent systemic sepsis. When recognition is delayed or if the patient is systemically ill, esophageal diversion may be required with staged reconstruction at a later time.
Although the native esophagus can be preserved in most cases, severe stricture formation that does not respond to dilation is best managed by esophageal replacement. The most commonly used options for esophageal substitution are the colon (right colon or transverse/left colon) and the stomach (gastric tube or gastric pull-up). Pedicled or free grafts of the jejunum are less commonly used. The right colon is based on a pedicle of the middle colic artery, and the left colon on a pedicle of the middle colic or left colic artery. Gastric tubes are fashioned from the greater curvature of the stomach based on the pedicle of the left gastroepiploic artery. When the entire stomach is used, as in gastric pull-up, the blood supply is provided by the right gastric artery. The neoesophagus may traverse: (a) substernally; (b) through a transthoracic route; or (c) through the posterior mediastinum to reach the neck. A feeding jejunostomy is placed at the time of surgery, and tube feedings are instituted once the postoperative ileus has resolved. In a recent review of patients treated by gastric pull-up, long-term outcome was very good. Complications included esophagogastric anastomotic leak (n = 15, 36%), which uniformly resolved without intervention, and stricture formation (n = 20, 49%), which responded to a course of dilation. Long-term follow-up has shown that all methods of esophageal substitution can support normal growth and development, and the children enjoy reasonably normal eating habits. Because of the potential for late complications such as ulceration and stricture, follow-up into adulthood is mandatory, but complications appear to diminish with time.
Gastroesophageal reflux (GER) occurs to some degree in all children and refers to the passage of gastric contents into the esophagus. By contrast, gastroesophageal reflux disease (GERD) describes the situation where reflux is symptomatic. Typical symptoms include failure to thrive, bleeding, stricture formation, reactive airway disease, aspiration pneumonia, and apnea. Failure to thrive and pulmonary problems are particularly common in infants with GERD, whereas strictures and esophagitis are more common in older children and adolescents. GERD is particularly problematic in neurologically impaired children.
Because all infants experience occasional episodes of GER to some degree, care must be taken before a child is labeled as having pathologic reflux. A history of repeated episodes of vomiting that interferes with growth and development or the presence of apparent life-threatening events is required for the diagnosis of GERD. In older children, esophageal bleeding, stricture formation, severe heartburn, or the development of Barrett's esophagus unequivocally connotes pathologic reflux or GERD. In neurologically impaired children, vomiting due to GER must be distinguished from chronic retching.
The workup of patients suspected of having GERD includes documentation of the episodes of reflux and evaluation of the anatomy. A barium swallow should be performed as an initial test. This will determine whether there is obstruction of the stomach or duodenum (due to duodenal webs or pyloric stenosis) and will determine whether malrotation is present. The frequency and severity of reflux should be assessed using a 24-hour pH probe study. Although this test is poorly tolerated, it provides the most accurate determination that GERD is present. Esophageal endoscopy with biopsies may identify the presence of esophagitis and is useful to determine the length of intra-abdominal esophagus and the presence of Barrett's esophagus. Some surgeons obtain a radioisotope "milk scan" to evaluate gastric emptying, although there is little evidence to show that this test changes management when a diagnosis of GERD has been confirmed using the above modalities.
Most patients with GERD are treated initially by conservative means. In the infant, propping and thickening the formula with rice cereal are generally recommended. Some authors prefer a prone, head-up position. In the infant unresponsive to position and formula changes and the older child with severe GERD, medical therapy is based on gastric acid reduction with an H2-blocking agent and/or a proton pump inhibitor. Medical therapy is successful in most neurologically normal infants and younger children, many of whom will outgrow their need for medications. In certain patients, however, medical treatment does not provide symptomatic relief, and surgery is therefore indicated. The least invasive surgical option includes the placement of a nasojejunal or gastrojejunal feeding tube. Because the stomach is bypassed, food contents do not enter the esophagus, and symptoms are often improved. However, as a long-term remedy, this therapy is associated with several problems. The tubes often become dislodged, acid reflux still occurs, and bolus feeding is generally not possible. Fundoplication provides definitive treatment for GER and is highly effective in most circumstances. The fundus may be wrapped around the distal esophagus either 360° (i.e., Nissen) or to lesser degrees (i.e., Thal or Toupet). At present, the standard approach in most children is to perform these procedures laparoscopically whenever possible. In children with feeding difficulties and in infants under 1 year of age, a gastrostomy tube should be placed at the time of surgery. Early postoperative complications include pneumonia and atelectasis, often due to inadequate pulmonary toilet and pain control with abdominal splinting. Late postoperative complications include wrap breakdown with recurrent reflux, which may require repeat fundoplication, and dysphagia due to a wrap performed too tightly, which generally responds to dilation. These complications are more common in children with neurologic impairment. The keys to successful surgical management of patients with GERD include careful patient selection and meticulous operative technique.
An Approach to the Vomiting Infant
The majority of infants vomit. Because infant vomiting is so common, it is important to differentiate between normal vomiting, which occurs in almost all babies, to some degree, and abnormal vomiting, which may be indicative of a potentially serious underlying disorder. To determine the seriousness of a particular infant's bouts of emesis, one needs to characterize what the vomit looks like and how sick the baby is. Vomit that looks like feeds and comes up immediately after a feeding is almost always gastroesophageal reflux. This may or may not be of concern, as described earlier. Vomiting that occurs a short while after feeding or vomiting that projects out of the baby's mouth may be indicative of pyloric stenosis. By contrast, vomit that has any green color in it is always worrisome. This may be reflective of intestinal volvulus, an underlying infection, or some other cause of intestinal obstruction. A more detailed description of the management of these conditions is provided in the following sections.
Hypertrophic Pyloric Stenosis
Infants with hypertrophic pyloric stenosis (HPS) typically present with nonbilious vomiting that becomes increasingly projectile over the course of several days to weeks due to progressive thickening of the pylorus muscle. HPS occurs in approximately 1 in 300 live births and commonly in infants between 3 and 6 weeks of age. Male-to-female ratio is nearly 5:1.
Eventually, as the pyloric muscle thickening progresses, the infant develops a complete gastric outlet obstruction and is no longer able to tolerate any feeds. Over time, the infant becomes increasingly hungry, unsuccessfully feeds repeatedly, and becomes increasingly dehydrated. Wet diapers become less frequent, and there may even be a perception of less passage of flatus. HPS may be associated with jaundice due to an indirect hyperbilirubinemia, although the nature of this relationship is unclear.
The cause of HPS has not been determined. Studies have shown that HPS is found in several generations of the same family, suggesting a familial link. Administration of erythromycin in early infancy has been linked to the subsequent development of HPS, although the cause is unclear. Infant positioning in the prone position was implicated as a cause of HPS particularly when, in Denmark and Sweden, a drop in both cases of sudden infant death syndrome (SIDS) and HPS were reported. More recently, a similar drop in both SIDS and HPS was noted in Germany, although the distribution of case rate declines were different across regions in Germany, suggesting that the etiology of HPS is not likely simply due to positioning.
Infants with HPS develop a hypochloremic, hypokalemic metabolic alkalosis. The urine pH level is high initially, but eventually drops because hydrogen ions are preferentially exchanged for sodium ions in the distal tubule of the kidney as the hypochloremia becomes severe (paradoxical aciduria). The diagnosis of pyloric stenosis usually can be made on physical examination by palpation of the typical "olive" in the right upper quadrant and the presence of visible gastric waves on the abdomen. When the olive cannot be palpated, US can diagnose the condition accurately in 95% of patients. Criteria for US diagnosis include a channel length of over 16 mm and pyloric thickness over 4 mm.
Given frequent fluid and electrolyte abnormalities at time of presentation, pyloric stenosis is never a surgical emergency. Fluid resuscitation with correction of electrolyte abnormalities and metabolic alkalosis is essential prior to induction of general anesthesia for operation. For most infants, fluid containing 5% dextrose and 0.45% saline with added potassium of 2 to 4 mEq/kg over 24 hours at a rate of approximately 150 to 175 mL/kg per 24 hours will correct the underlying deficit. It is important to ensure that the child has an adequate urine output (>2 cc/kg/h) as further evidence that rehydration has occurred. After resuscitation, a Fredet-Ramstedt pyloromyotomy is performed (Fig. 39-12). It may be performed using an open or laparoscopic approach. The open pyloromyotomy is performed through either an umbilical or a right upper quadrant transverse abdominal incision. The former route is cosmetically more appealing, although the transverse incision provides easier access to the antrum and pylorus. In recent years, the laparoscopic approach has gained great popularity. Two randomized trials have demonstrated that both the open and laparoscopic approaches may be performed safely with equal incidence of postoperative complications, although the cosmetic result is clearly superior with the laparoscopic approach. Whether done through an open or laparoscopic approach, surgical treatment of pyloric stenosis involves splitting the pyloric muscle while leaving the underlying submucosa intact. The incision extends from just proximal to the pyloric vein of Mayo to the gastric antrum; it typically measures between 1 and 2 cm in length. Postoperatively, IV fluids are continued for several hours, after which Pedialyte is offered, followed by formula or breast milk, which is gradually increased to 60 cc every 3 hours. Most infants can be discharged home within 24–48 hours following surgery. Recently, several authors have shown that ad lib feeds are safely tolerated by the neonate and result in a shorter hospital stay.
Fredet-Ramstedt pyloromyotomy. A. Pylorus delivered into wound and seromuscular layer incised. B. Seromuscular layer separated down to submucosal base to permit herniation of mucosa through pyloric incision. C. Cross-section demonstrating hypertrophied pylorus, depth of incision, and spreading of muscle to permit mucosa to herniate through incision.
The complications of pyloromyotomy include perforation of the mucosa (1%–3%), bleeding, wound infection, and recurrent symptoms due to inadequate myotomy. When perforation occurs, the mucosa is repaired with a stitch that is placed to tack the mucosa down and reapproximate the serosa in the region of the tear. A nasogastric tube is left in place for 24 hours. The outcome is generally very good.
Intestinal Obstruction in the Newborn
The cardinal symptom of intestinal obstruction in the newborn is bilious emesis. Prompt recognition and treatment of neonatal intestinal obstruction can truly be life saving.
The incidence of neonatal intestinal obstruction is 1 in 2000 live births. The approach to intestinal obstruction in the newborn infant is critical for timely and appropriate intervention. When a neonate develops bilious vomiting, one must consider a surgical etiology. Indeed, the majority of newborns with bilious emesis have a surgical condition. In evaluating a potential intestinal obstruction, it is helpful to determine whether the intestinal obstruction is either proximal or distal to the ligament of Treitz. One must conduct a detailed prenatal and immediate postnatal history and a thorough physical examination. In all cases of intestinal obstruction, it is vital to obtain abdominal films in the supine and upright (or lateral decubitus) views to assess the presence of air-fluid levels or free air as well as how far downstream air has managed to travel. Importantly, one should recognize that it is difficult to determine whether a loop of bowel is part of either the small or large intestine, as neonatal bowel lacks clear features, such as haustra or plica circulares, normally present in older children or adults. As such, contrast imaging may be necessary for diagnosis in some instances.
Proximal intestinal obstructions typically present with bilious emesis and minimal abdominal distention. The normal neonate should have a rounded, soft abdomen; in contrast, a neonate with a proximal intestinal obstruction typically exhibits a flat or scaphoid abdomen. On a series of upright and supine abdominal radiographs, one may see a paucity or absence of bowel gas, which normally should be present throughout the gastrointestinal tract within 24 hours. Of utmost importance is the exclusion of a malrotation with midgut volvulus from all other intestinal obstructions as this is a surgical emergency.
Distal obstructions typically presents with bilious emesis and abdominal distention. Passage of black-green meconium should have occurred within the first 24 to 38 hours. Of great importance, one should determine whether or not there is tenderness or discoloration of the abdomen, visible or palpable loops of intestine, and presence or absence of a mass, and whether or not the anus is patent and in the appropriate location. Abdominal radiographs may demonstrate calcifications, which may indicate complicated meconium ileus; pneumatosis and/or pneumoperitoneum may indicate necrotizing enterocolitis. A contrast enema may show whether there is a microcolon indicative of jejunoileal atresia or meconium ileus. If a microcolon is not present, then the diagnoses of Hirschsprung's disease, small left colon syndrome, or meconium plug syndrome should be considered.
Duodenal Obstruction
Whenever the diagnosis of duodenal obstruction is entertained, malrotation and midgut volvulus must be excluded. This topic is covered in further detail later in this chapter. Other causes of duodenal obstruction include duodenal atresia, duodenal web, stenosis, annular pancreas, or duodenal duplication cyst. Duodenal obstruction is easily diagnosed on prenatal US, which demonstrates the fluid-filled stomach and proximal duodenum as two discrete cystic structures in the upper abdomen. Associated polyhydramnios is common and presents in the third trimester. In 85% of infants with duodenal obstruction, the entry of the bile duct is proximal to the level of obstruction, such that vomiting is bilious. Abdominal distention is typically not present because of the proximal level of obstruction. In infants with obstruction proximal to the bile duct entry, the vomiting is nonbilious. The classic finding on abdominal radiography is the "double bubble" sign, which represents the dilated stomach and duodenum (Fig. 39-13). In association with the appropriate clinical picture, this finding is sufficient to confirm the diagnosis of duodenal obstruction. However, if there is any uncertainty, particularly when a partial obstruction is suspected, a contrast upper gastrointestinal series is diagnostic.
Abdominal x-ray showing "double bubble" sign in a newborn infant with duodenal atresia. The two "bubbles" are numbered.
An orogastric tube is inserted to decompress the stomach and duodenum, and the infant is given IV fluids to maintain adequate urine output. If the infant appears ill or if abdominal tenderness is present, a diagnosis of malrotation and midgut volvulus should be considered, and surgery should not be delayed. Typically, the abdomen is soft, and the infant is very stable. Under these circumstances, the infant should be evaluated thoroughly for other associated anomalies. Approximately one third of newborns with duodenal atresia have associated Down syndrome (trisomy 21). These patients should be evaluated for associated cardiac anomalies. Once the workup is complete and the infant is stable, he or she is taken to the operating room, and the abdomen is entered through a transverse right upper quadrant supraumbilical incision under general endotracheal anesthesia. Associated anomalies should be searched for at the time of the operation. These include malrotation, anterior portal vein, a second distal web, and biliary atresia. The surgical treatment of choice for duodenal obstruction due to duodenal stenosis or atresia or annular pancreas is a duodeno-duodenostomy. This procedure can be most easily performed using a proximal transverse-to-distal longitudinal (diamond-shaped) anastomosis. In cases where the duodenum is extremely dilated, the lumen may be tapered using a linear stapler with a large Foley catheter (24 F or greater) in the duodenal lumen. It is important to emphasize that an annular pancreas is never divided but rather is bypassed to avoid injury to the pancreatic ducts. Treatment of duodenal web includes vertical duodenotomy, excision of the web, oversewing of the mucosa, and closing the duodenotomy horizontally. Gastrostomy tube placement is not routinely performed. Recently reported survival rates exceed 90%. Late complications from repair of duodenal atresia occur in approximately 12% to 15% of patients and include megaduodenum, intestinal motility disorders, and GER.
Intestinal Atresia
Obstruction due to intestinal atresia can occur at any point along the intestinal tract. Intestinal atresias were previously thought to be the result of in utero mesenteric vascular accidents leading to segmental loss of the intestinal lumen, although, more likely they are due to developmental defects in normal intestinal organogenesis due to disruption of various signaling pathways such as fibroblast growth factor, bone morphogenic protein, and β-catenin pathways. The incidence of intestinal atresia has been estimated to be between 1 in 2000 and 1 in 5000 live births, with equal representation of the sexes. Infants with jejunal or ileal atresia present with bilious vomiting and progressive abdominal distention. The more distal the obstruction, the more distended the abdomen becomes, and the greater is the number of obstructed loops on upright abdominal films (Fig. 39-14).
Intestinal obstruction in the newborn showing several loops of distended bowel with air-fluid levels. This child has jejunal atresia.
In cases where the diagnosis of complete intestinal obstruction is ascertained by the clinical picture and the presence of staggered air-fluid levels on plain abdominal films, the child can be brought to the operating room after appropriate resuscitation. In these circumstances, there is little extra information to be gained by performing a barium enema. By contrast, when there is diagnostic uncertainty or when distal intestinal obstruction is apparent, a barium enema is useful to establish whether a microcolon is present and to diagnose the presence of meconium plugs, small left colon syndrome, Hirschsprung's disease, or meconium ileus. Judicious use of barium enema is therefore required in order to safely manage neonatal intestinal obstruction, based on an understanding of the expected level of obstruction.
Surgical correction of the small intestinal atresia should be performed urgently. At laparotomy, one of several types of atresia will be encountered. In type 1, there is a mucosal atresia with intact muscularis. In type 2, the atretic ends are connected by a fibrous band. In type 3A, the two ends of the atresia are separated by a V-shaped defect in the mesentery. Type 3B is an "apple peel" deformity or "Christmas tree" deformity in which the bowel distal to the atresia receives its blood supply in a retrograde fashion from the ileocolic or right colic artery (Fig. 39-15). In type 4 atresia, there are multiple atresias with a "string of sausage" or "string of beads" appearance. Disparity in lumen size between the proximal distended bowel and the small diameter of collapsed bowel distal to the atresia has led to a number of innovative techniques of anastomosis. However, under most circumstances, an anastomosis can be performed using the end-to-back technique in which the distal, compressed loop is "fish-mouthed" along its antimesenteric border. The proximal distended loop can be tapered as described earlier. Because the distended proximal bowel rarely has normal motility, the extremely dilated portion should be resected prior to performing the anastomosis.
Operative photograph of newborn with "Christmas tree" type of ileal atresia.
Occasionally the infant with intestinal atresia will develop ischemia or necrosis of the proximal segment secondary to volvulus of the dilated, bulbous, blind-ending proximal bowel. Under these conditions, an end ileostomy and mucus fistula should be created, and the anastomosis should be deferred to another time after the infant stabilizes.
Malrotation and Midgut Volvulus
During the sixth week of fetal development, the midgut grows too rapidly to be accommodated in the abdominal cavity and therefore herniates into the umbilical cord. Between the tenth and twelfth weeks, the midgut returns to the abdominal cavity, undergoing a 270° counterclockwise rotation around the superior mesenteric artery. Because the duodenum also rotates caudal to the artery, it acquires a C-loop that traces this path. The cecum rotates cephalad to the artery, which determines the location of the transverse and ascending colon. Subsequently, the duodenum becomes fixed retroperitoneally in its third portion and at the ligament of Treitz, while the cecum becomes fixed to the lateral abdominal wall by peritoneal bands. The takeoff of the branches of the superior mesenteric artery elongates and becomes fixed along a line extending from its emergence from the aorta to the cecum in the right lower quadrant. Genetic mutations likely disrupt the signaling critical for normal intestinal rotation. For instance, mutations in the gene BCL6 resulting in absence of left-sided expression of its transcript lead to reversed cardiac orientation, defective ocular development, and malrotation. The essential role of the dorsal gut mesentery in mediating normal intestinal rotation and the role of the forkhead box transcription factor Foxf1 in formation of the dorsal mesentery in mice are consistent with the noted association of intestinal malrotation with alveolar capillary dysplasia, caused by mutations in FOXF1. If rotation is incomplete, the cecum remains in the epigastrium, but the bands fixing the duodenum to the retroperitoneum and cecum continue to form. This results in (Ladd's) bands extending from the cecum to the lateral abdominal wall and crossing the duodenum, which creates the potential for obstruction. The mesenteric takeoff remains confined to the epigastrium, resulting in a narrow pedicle suspending all the branches of the superior mesenteric artery and the entire midgut. A volvulus may therefore occur around the mesentery. This twist not only obstructs the proximal jejunum, but also cuts off the blood supply to the midgut. Intestinal obstruction and complete infarction of the midgut occur unless the problem is promptly corrected surgically.
Presentation and Management
Midgut volvulus can occur at any age, although it is seen most often in the first few weeks of life. Bilious vomiting is usually the first sign of volvulus, and all infants with bilious vomiting must be evaluated rapidly to ensure that they do not have intestinal malrotation with volvulus. The child with irritability and bilious emesis should raise particular suspicions for this diagnosis. If left untreated, vascular compromise of the midgut initially causes bloody stools, but eventually results in circulatory collapse. Additional clues to the presence of advanced ischemia of the intestine include erythema and edema of the abdominal wall, which progresses to shock and death. It must be re-emphasized that the index of suspicion for this condition must be high, since abdominal signs are minimal in the early stages. Abdominal films show a paucity of gas throughout the intestine with a few scattered air-fluid levels (Fig. 39-16). When these findings are present, the patient should undergo immediate fluid resuscitation to ensure adequate perfusion and urine output followed by prompt exploratory laparotomy. In cases where the child is stable, laparoscopy may be considered.
Abdominal x-ray of a 10-day-old infant with bilious emesis. Note the dilated proximal bowel and the paucity of distal bowel gas, characteristic of a volvulus.
Often the patient will not appear ill, and the plain films may suggest partial duodenal obstruction. Under these conditions, the patient may have malrotation without volvulus. This is best diagnosed by an upper gastrointestinal series that shows incomplete rotation with the duodenojejunal junction displaced to the right. The duodenum may show a corkscrew effect diagnosing volvulus or complete duodenal obstruction, with the small bowel loops entirely in the right side of the abdomen. Barium enema may show a displaced cecum, but this sign is unreliable, especially in the small infant in whom the cecum is normally in a somewhat higher position than in the older child.
When volvulus is suspected, early surgical intervention is mandatory if the ischemic process is to be avoided or reversed. Volvulus occurs clockwise and is therefore untwisted counterclockwise. This can be remembered using the memory aid "turn back the hands of time." Subsequently, a Ladd procedure is performed. This operation does not correct the malrotation, but does broaden the narrow mesenteric pedicle to prevent volvulus from recurring. This procedure is performed as follows (Fig. 39-17). The bands between the cecum and the abdominal wall and between the duodenum and terminal ileum are divided sharply to splay out the superior mesenteric artery and its branches. This maneuver brings the straightened duodenum into the right lower quadrant and the cecum into the left lower quadrant. The appendix is removed to avoid diagnostic errors in later life. No attempt is made to suture the cecum or duodenum in place. With advanced ischemia, reduction of the volvulus without the Ladd procedure is accomplished, and a "second look" 24 to 36 hours later often will show some vascular recovery. A plastic transparent silo may be placed to facilitate constant evaluation of the intestine and to plan for the timing of re-exploration. Frankly necrotic bowel can then be resected conservatively. With early diagnosis and correction the prognosis is excellent. However, diagnostic delay can lead to mortality or to short-gut syndrome requiring intestinal transplantation.
Ladd procedure for malrotation. A. Lysis of cecal and duodenal bands. B. Broadening the mesentery. C. Appendectomy.
A subset of patients with malrotation will demonstrate chronic obstructive symptoms. These symptoms may result from Ladd's bands across the duodenum or, occasionally, from intermittent volvulus. Symptoms include intermittent abdominal pain and intermittent vomiting, which may occasionally be bilious. Infants with malrotation may demonstrate failure to thrive, and they may be diagnosed initially as having GERD. Surgical correction using the Ladd procedure, as described earlier, can prevent volvulus from occurring and improve symptoms in many instances.
Meconium Ileus
Pathogenesis and Clinical Presentation
Infants with cystic fibrosis have characteristic pancreatic enzyme deficiencies and abnormal chloride secretion in the intestine that result in the production of viscous, water-poor meconium. This phenotype is explained by the presence of mutations in the CFTR gene. Meconium ileus occurs when this thick, highly viscous meconium becomes impacted in the ileum and leads to high-grade intestinal obstruction. Recently, additional mutations were recently identified in genes encoding multiple apical plasma membrane proteins of infants with meconium ileus. Meconium ileus can be either uncomplicated, in which there is no intestinal perforation, or complicated, in which prenatal perforation of the intestine has occurred or vascular compromise of the distended ileum develops. Antenatal US may reveal the presence of intra-abdominal or scrotal calcifications or distended bowel loops. These infants present shortly after birth with progressive abdominal distention and failure to pass meconium with intermittent bilious emesis. Abdominal radiographs show dilated loops of intestine. Because the enteric contents are so viscous, air-fluid levels do not form, even when obstruction is complete. Small bubbles of gas become entrapped in the inspissated meconium in the distal ileum, where they produce a characteristic "ground glass" appearance.
The diagnosis of meconium ileus is confirmed by a contrast enema, which typically demonstrates a microcolon. In patients with uncomplicated meconium ileus, the terminal ileum is filled with pellets of meconium. In patients with complicated meconium ileus, intraperitoneal calcifications form, producing an eggshell pattern on plain abdominal x-ray.
The treatment strategy depends on whether the patient has complicated or uncomplicated meconium ileus. Patients with uncomplicated meconium ileus can be treated nonoperatively. Either dilute water-soluble contrast or N-acetylcysteine (Mucomyst¯) is infused transanally via catheter under fluoroscopic control into the dilated portion of the ileum. Because these agents act by absorbing fluid from the bowel wall into the intestinal lumen, infants undergoing treatment are at risk of fluid and electrolyte abnormalities, so appropriate resuscitation of the infant during this maneuver is extremely important. The enema may be repeated at 12-hour intervals over several days until all the meconium is evacuated. Inability to reflux the contrast into the dilated portion of the ileum signifies the presence of an associated atresia or complicated meconium ileus, and thus warrants exploratory laparotomy. If surgical intervention is required because of failure of contrast enemas to relieve obstruction, operative irrigation with dilute contrast agent, N-acetylcysteine, or saline through a purse-string suture may be successful. Alternatively, resection of the distended terminal ileum is performed, and the meconium pellets are flushed from the distal small bowel. At this point, an end ileostomy may be created. The distal bowel may be brought up as a mucus fistula or sewn to the side of the ileum as a Bishop-Koop anastomosis. An end-to-end anastomosis may also be considered in the appropriate setting (Fig. 39-18).
Techniques of intestinal anastomosis for infants with small bowel obstruction. A. End to back: distal limb has been incised, creating "fish mouth" to enlarge the lumen. B. Bishop-Koop: proximal distended limb joined to side of distal small bowel, which is vented by "chimney" to the abdominal wall. C. Tapering: portion of antimesenteric wall of proximal bowel excised, with longitudinal closure to minimize disparity in the limbs. D. Mikulicz double-barreled enterostomy is constructed by suturing the two limbs together and then exteriorizing the double stoma. The common wall can be crushed with a special clamp to create a large stoma. The stoma can be closed in an extraperitoneal manner.
Necrotizing Enterocolitis
Necrotizing enterocolitis (NEC) is the most frequent and lethal gastrointestinal disorder affecting the intestine of the stressed, preterm neonate. Over 25,000 cases of NEC are reported annually. The overall mortality ranges between 10% and 50%. Advances in neonatal care such as surfactant therapy and improved methods of mechanical ventilation have resulted in increasing numbers of low birth weight infants surviving neonatal hyaline membrane disease. An increasing proportion of survivors of neonatal respiratory distress syndrome will therefore be at risk for developing NEC. Consequently, it is estimated that NEC soon will surpass respiratory distress syndrome as the principal cause of death in the preterm infant.
Multiple risk factors have been associated with the development of NEC. These include prematurity, initiation of enteral feeding, bacterial infection, intestinal ischemia resulting from birth asphyxia, umbilical artery cannulation, persistence of a patent ductus arteriosus, cyanotic heart disease, and maternal cocaine abuse. Nonetheless, the mechanisms by which these complex interacting etiologies lead to the development of the disease remain undefined. The only consistent epidemiologic precursors for NEC are prematurity and enteral alimentation, representing the commonly encountered clinical situation of a stressed infant who is fed enterally. Of note, there is some debate regarding the type and strategy of enteral alimentation in the pathogenesis of NEC. A prospective randomized study showed no increase in the incidence of NEC despite an aggressive feeding strategy.
The indigenous intestinal microbial flora has been postulated to play a central role in the pathogenesis of NEC. Bacterial colonization may be a prerequisite for the development of this disease because oral prophylaxis with vancomycin or gentamicin reduced the incidence of NEC. The importance of bacteria in the pathogenesis of NEC is further supported by the finding that NEC occurs in episodic waves that can be abrogated by infection control measures and the fact that NEC usually develops at least 10 days postnatally, when the gastrointestinal tract is colonized by coliforms. More recently, outbreaks of NEC have been reported in infants fed formula contaminated with Cronobacter sakazakii. Common bacterial isolates from the blood, peritoneal fluid, and stool of infants with advanced NEC include Escherichia coli, Enterobacter, Klebsiella, and occasionally, coagulase-negative Staphylococcus species.
NEC may involve single or multiple segments of the intestine, most commonly the terminal ileum, followed by the colon. The gross findings in NEC include bowel distention with patchy areas of thinning, pneumatosis, gangrene, or frank perforation. The microscopic features include the appearance of a "bland infarct" characterized by full-thickness necrosis.
Infants with NEC present with a spectrum of disease. In general, the infants are premature and may have sustained one or more episodes of stress, such as birth asphyxia, or they may have congenital cardiac disease. The clinical picture of NEC has been characterized by Bell and colleagues as progressing from a period of mild illness to that of severe, life-threatening sepsis. Although not all infants progress through the various "Bell stages," this classification scheme provides a useful format to describe the clinical picture associated with the development of NEC. In the earliest stage (Bell stage I), infants present with feeding intolerance. This is suggested by vomiting or by the presence of a large residual volume from a previous feeding in the stomach at the time of the next feeding. Following appropriate treatment, which consists of bowel rest and IV antibiotics, many of these infants will not progress to more advanced stages of NEC. These infants are colloquially described as suffering from a "NEC scare" and represent a population of neonates who are at risk of developing more severe NEC if a more prolonged period of stress supervenes.
Infants with Bell stage II have established NEC that is not immediately life threatening. Clinical findings include abdominal distention and tenderness, bilious nasogastric aspirate, and bloody stools. These findings indicate the development of intestinal ileus and mucosal ischemia, respectively. Abdominal examination may reveal a palpable mass indicating the presence of an inflamed loop of bowel, diffuse abdominal tenderness, cellulitis, and edema of the anterior abdominal wall. The infant may appear systemically ill, with decreased urine output, hypotension, tachycardia, and noncardiac pulmonary edema. Hematologic evaluation reveals either leukocytosis or leukopenia, an increase in the number of bands, and thrombocytopenia. An increase in the blood urea nitrogen and plasma creatinine levels may be found, which signifies the development of renal dysfunction. The diagnosis of NEC may be confirmed by abdominal radiography. The pathognomonic radiographic finding in NEC is pneumatosis intestinalis, which represents invasion of the ischemic mucosa by gas-producing microbes (Fig. 39-19). Other findings include the presence of ileus or portal venous gas. The latter is a transient finding that indicates the presence of severe NEC with intestinal necrosis. A fixed loop of bowel may be seen on serial abdominal radiographs, which suggests the possibility that a diseased loop of bowel, potentially with a localized perforation, is present. Although these infants are at risk of progressing to more severe disease, with timely and appropriate treatment, they often recover.
Abdominal radiograph of infant with necrotizing enterocolitis. Arrows point to area of pneumatosis intestinalis.
Infants with Bell stage III have the most advanced form of NEC. Abdominal radiographs often demonstrate the presence of pneumoperitoneum, indicating that intestinal perforation has occurred. These patients may develop a fulminant course with progressive peritonitis, acidosis, sepsis, disseminated intravascular coagulopathy, and death.
Pathogenesis of Necrotizing Enterocolitis
Several theories have been proposed to explain the development of NEC. To more precisely understand the mechanisms that contribute to the pathogenesis of NEC, several groups have focused on understanding the potential clues that may be revealed by studying patients who have progressed from Bell stage I to Bell stage III disease. In general terms, the development of diffuse pneumatosis intestinalis, which is associated with the development of stage II NEC, is thought to be due to the presence of gas within the wall of the intestine from enteric bacteria, suggesting the causative role of bacteria in the pathogenesis of NEC. Furthermore, the development of pneumoperitoneum indicates disease progression with severe disruption of the intestinal barrier (intestinal perforation). Finally, systemic sepsis with diffuse multisystem organ dysfunction suggests the role for circulating proinflammatory cytokines in the pathogenesis of NEC. It has also been demonstrated that the premature intestine responds in an exaggerated fashion to bacterial products, rendering the host susceptible to barrier dysfunction and the development of NEC. As was recently summarized by the 2006 National Institute of Child Health and Development (NICHD) workshop on NEC research, "NEC can be thought to arise from an uncontrolled exuberant inflammatory response to bacterial colonization that characterizes the intestine of premature infants."
In all infants suspected of having NEC, feedings are discontinued, a nasogastric tube is placed, and broad-spectrum parenteral antibiotics are given. The infant is resuscitated, and inotropes are administered to maintain perfusion as needed. Intubation and mechanical ventilation may be required to maintain oxygenation. TPN is started. Subsequent treatment may be influenced by the particular stage of NEC that is present. Patients with Bell stage I are closely monitored and generally remain NPO (nothing by mouth) and on IV antibiotics for 5 to 7 days, prior to reinitiating enteral nutrition. If the infant fully recovers, feedings may be reinitiated.
Patients with Bell stage II disease merit close observation. Serial physical examinations are performed looking for the development of diffuse peritonitis, a fixed mass, progressive abdominal wall cellulitis, or systemic sepsis. Serial abdominal radiographs are obtained at regular intervals to look for the presence of pneumoperitoneum or a fixed loop of bowel. If infants fail to improve after several days of treatment or if abdominal radiographs show a fixed intestinal loop, consideration should be given to exploratory laparotomy. Paracentesis may be performed, and if the Gram stain demonstrates multiple organisms and leukocytes, perforation of the bowel should be suspected, and patients should undergo laparotomy.
In the most severe form of NEC (Bell stage III), patients have definite intestinal perforation or have not responded to nonoperative therapy. Two schools of thought direct further management. One group favors exploratory laparotomy. At laparotomy, frankly gangrenous or perforated bowel is resected, and the intestinal ends are brought out as stomas. When there is massive intestinal involvement, marginally viable bowel is retained, and a "second look" procedure is carried out after the infant stabilizes (24–48 hours). Patients with extensive necrosis at the second look may be managed by placing a proximal diverting stoma, resecting bowel that is definitely not viable, and leaving questionably viable bowel behind, distal to the diverted segment. When the intestine is viable except for a localized perforation without diffuse peritonitis and if the infant's clinical condition permits, intestinal anastomosis may be performed. In cases where the diseased, perforated segment cannot be safely resected, drainage catheters may be left in the region of the diseased bowel, and the infant is allowed to stabilize.
An alternative approach to the management of infants with perforated NEC involves drainage of the peritoneal cavity. This may be performed under local anesthesia at the bedside and can be an effective means of stabilizing the desperately ill infant by relieving increased intra-abdominal pressure and allowing ventilation. When successful, this method also allows for drainage of perforated bowel by establishing a controlled fistula. Approximately one third of infants treated with drainage alone survive without requiring additional operations. Infants who do not respond to peritoneal drainage alone after 48 to 72 hours should undergo laparotomy. This procedure allows for the resection of frankly necrotic bowel diversion of the fecal stream and facilitates more effective drainage. It is noteworthy that a recent randomized controlled trial demonstrated that outcomes were similar in infants with NEC who were treated either with primary peritoneal drainage or laparotomy.
Necrotizing Enterocolitis in Older Infants
Although NEC is typically a disease that affects preterm infants, several independent groups have reported a tendency for early onset of NEC in term and near-term infants. In these patients, the pattern of disease was found to be different from that found in premature infants. Specifically, NEC in older infants typically is localized to the end of the small intestine and beginning of the colon, suggestive of an ischemic pathophysiology. There are four pertinent associations that are observed in term infants who develop NEC: congenital heart disease, in utero growth restriction, polycythemia, and perinatal hypoxic-ischemic events. As with NEC in preterm infants, NEC in older patients is also associated with formula consumption and is very rare in exclusively breast-fed infants. Patients with NEC at full term typically present with bloody stools and may be characterized by rapid onset of symptoms and a fulminant course. Thus, although it is true that NEC is typically a disease of premature babies, in the appropriate setting, NEC can develop at any age.
Spontaneous Intestinal Perforation Versus Necrotizing Enterocolitis
In addition to NEC, preterm infants with intestinal pathology may develop spontaneous intestinal perforation (SIP). SIP is a distinct clinical entity from NEC and is essentially a perforation in the terminal ileum. The histopathology of SIP is different from NEC. Specifically, the mucosa is intact and not necrotic, there is no sign of ischemia, and the submucosa is thinned at the site of perforation. In contrast to NEC, pneumatosis intestinalis is absent in SIP. Moreover, the demographics of NEC and SIP are slightly different, in that patients with SIP tend to be slightly more premature, smaller, and more likely to have been on inotropic support. However, both NEC and SIP occur with similar frequency in low birth weight infants. The outcome of patients in the two groups is slightly different. Because patients with SIP have isolated disease without necrosis or systemic inflammation, they tend to have a better outcome. In short, the diagnosis of SIP versus NEC has important prognostic significance. The treatment strategies, however, are essentially the same.
Survival in patients with NEC is dependent on the stage of disease, the extent of prematurity, and the presence of associated comorbidities. Survival by stage has recently been shown to be approximately 85%, 65%, and 35% for stages I, II, and III, respectively. Strictures develop in 20% of medically or surgically treated patients, and a contrast enema is mandatory before re-establishing intestinal continuity. If all other factors are favorable, the ileostomy is closed when the child is between 2 and 2.5 kg. At the time of stoma closure, the entire intestine should be examined to search for strictures. Patients who develop massive intestinal necrosis are at risk of developing short bowel syndrome, particularly when the total length of the viable intestinal segment is less than 40 cm. These patients require TPN to provide adequate calories for growth and development and may develop parenteral nutrition–associated cholestasis and hepatic fibrosis. In a significant number of these patients, transplantation of the liver and small bowel may be required.
Short Bowel Syndrome
Short bowel syndrome (SBS) is an expensive, morbid condition with an increasing incidence. Various congenital and perinatal acquired conditions such as gastroschisis, malrotation, atresia, and NEC may lead to SBS. NEC is the most common gastrointestinal emergency in neonates and primarily occurs in premature infants. As rates of prematurity are increasing, so are the numbers of children with SBS. Medical and surgical treatment options carry high dollar and human costs and morbidities including multiple infections and hospitalizations for vascular access, liver failure in conjunction with parenteral nutrition-associated cholestasis, and death. Small bowel transplant has a reported 5-year graft survival of 48%, but is attended by rejection, the morbidity of major surgery, and a lifelong need for antirejection medication. A report on 989 grafts in 923 patients by the Intestine Transplant Registry reveals improving outcomes, but 1-year graft and patient survival rates are 65% and 77%, respectively. If successful in the human, engineered intestine from autologous cells could avoid the problems of transplantation: donor supply and immunosuppression. Because engineered small and large intestine, esophagus, stomach, and specific portions of the gastrointestinal tract such as the gastroesophageal junction form by the same process, other intestinal deficiencies may possibly be addressed.
Intussusception
Intussusception is the leading cause of intestinal obstruction in the young child. It refers to the condition whereby a segment of intestine becomes drawn into the lumen of the more proximal bowel. The process usually begins in the region of the terminal ileum and extends distally into the ascending, transverse, or descending colon. Rarely, an intussusception may prolapse through the rectum.
The cause of intussusception is not clear, although one hypothesis suggests that hypertrophy of the Peyer's patches in the terminal ileum from an antecedent viral infection acts as a lead point. Peristaltic action of the intestine then causes the bowel distal to the lead point to invaginate into itself. Idiopathic intussusception occurs in children between the ages of approximately 6 and 24 months of age. Beyond this age group, one should consider the possibility that a pathologic lead point may be present. These include polyps, malignant tumors such as lymphoma, enteric duplication cysts, or Meckel's diverticulum. Such intussusceptions are rarely reduced by air or contrast enema, and thus the lead point is identified when operative reduction of the intussusception is performed.
Since intussusception is frequently preceded by a gastrointestinal viral illness, the onset may not be easily determined. Typically, the infant develops paroxysms of crampy abdominal pain and intermittent vomiting. Between attacks, the infant may act normally, but as symptoms progress, increasing lethargy develops. Bloody mucus ("currant jelly" stool) may be passed per rectum. Ultimately, if reduction is not accomplished, gangrene of the intussusceptum occurs, and perforation may ensue. On physical examination, an elongated mass is detected in the right upper quadrant or epigastrium with an absence of bowel in the right lower quadrant (Dance's sign). The mass may be seen on plain abdominal x-ray but is more easily demonstrated on air or contrast enema.
Patients with intussusception should be assessed for the presence of peritonitis and for the severity of systemic illness. Following resuscitation and administration of IV antibiotics, the child is assessed for suitability to proceed with radiographic versus surgical reduction. In the absence of peritonitis, the child should undergo radiographic reduction. If peritonitis is present or if the child appears systemically ill, urgent laparotomy is indicated.
In the stable patient, the air enema is diagnostic and may also be curative, and it is the preferred method of diagnosis and treatment of intussusception. Air is introduced with a manometer, and the pressure that is administered is carefully monitored. Under most instances, this should not exceed 120 mmHg. Successful reduction is marked by free reflux of air into multiple loops of small bowel and symptomatic improvement as the infant suddenly becomes pain free. Unless both of these signs are observed, it cannot be assumed that the intussusception is reduced. If reduction is unsuccessful and the infant remains stable, the infant should be brought back to the radiology suite for a repeat attempt at reduction after a few hours. This strategy has improved the success rate of nonoperative reduction in many centers. In addition, hydrostatic reduction with barium may be useful if pneumatic reduction is unsuccessful. The overall success rate of radiographic reduction varies based on the experience of the center and is typically between 60% and 90%.
If nonoperative reduction is successful, the infant may be given oral fluids after a period of observation. Failure to reduce the intussusception mandates surgery. Two approaches are used. In an open procedure, exploration is carried out through a right lower quadrant incision, delivering the intussuscepted mass into the wound. Reduction usually can be accomplished by gentle distal pressure, where the intussusceptum is gently milked out of the intussuscipiens (Fig. 39-20). Care should be taken not to pull the bowel out, as this can cause damage to the bowel wall. The blood supply to the appendix is often compromised, and appendectomy is performed. If the bowel is frankly gangrenous, resection and primary anastomosis are performed. In experienced hands, laparoscopic reduction may be performed, even in very young infants. This is performed using a 5-mm laparoscope placed in the umbilicus and two additional 5-mm ports in the left and right lower quadrants. The bowel is inspected, and if it appears to be viable, reduction is performed by milking the bowel or using gentle traction, although this approach is normally discouraged during manual reduction. Atraumatic bowel graspers allow the bowel to be handled without injuring it.
Open reduction of intussusception showing how the bowel is milked backward to relieve the obstruction.
IV fluids are continued until the postoperative ileus subsides. Patients are started on clear liquids, and their diet is advanced as tolerated. Of note, recurrent intussusception occurs in 5% to 10% of patients, independent of whether the bowel is reduced radiographically or surgically. Patients present with recurrent symptoms in the immediate postoperative period. Treatment involves repeat air enema, which is successful in most cases. In patients who experience three or more episodes of intussusception, the presence of a pathologic lead point should be suspected and carefully evaluated using contrast studies. After the third episode of intussusception, many pediatric surgeons will perform an exploratory laparotomy to reduce the bowel and to resect a pathologic lead point if identified.
Correct diagnosis of appendicitis in children can be one of the most humbling and challenging tasks facing the pediatric surgeon. The classical presentation is known to all students and practitioners of surgery: generalized abdominal pain that localizes to the right lower quadrant followed by nausea, vomiting, fever, and localized peritoneal irritation in the region of McBurney's point. When children present in this manner, there should be little diagnostic delay. The child should be made NPO, administered IV fluids and broad-spectrum antibiotics, and brought to the operating room for an appendectomy. However, children often do not present in this manner. The coexistence of nonspecific viral syndromes and the inability of young children to describe the location and quality of their pain often result in diagnostic delay. As a result, children with appendicitis often present with perforation, particularly those who are under 5 years of age. Perforation increases the length of hospital stay and makes the overall course of the illness significantly more complex.
Diagnosis of Appendicitis in Children
Controversy exists regarding the role of radiographic studies in the diagnosis of acute appendicitis. Because children have less periappendiceal fat than adults, CT is less reliable in making the diagnosis. In addition, radiation exposure resulting from the CT scan may have potentially long-term adverse effects. Likewise, US is neither sufficiently sensitive nor specific to accurately make the diagnosis of appendicitis, although it is very useful for excluding ovarian causes of abdominal pain. Therefore, the diagnosis of appendicitis remains largely clinical, and each clinician should develop his or her own threshold to operate or to observe the patient. A reasonable practice guideline is as follows: When the diagnosis is clinically apparent, appendectomy should obviously be performed with minimal delay. Localized right lower quadrant tenderness associated with low-grade fever and leukocytosis in boys should prompt surgical exploration. In girls, ovarian or uterine pathology must also be considered. When there is diagnostic uncertainty, the child may be observed, rehydrated, and reassessed. In girls of menstruating age, US may be performed to exclude ovarian pathology (cysts, torsion, or tumor). If all studies are negative, yet the pain persists, and the abdominal findings remain equivocal, diagnostic laparoscopy may be employed to determine the etiology of the abdominal pain. The appendix should be removed even if it appears to be normal, unless another pathologic cause of the abdominal pain is definitively identified and the appendectomy would substantially increase morbidity.
Surgical Treatment of Appendicitis
The definitive treatment for acute appendicitis is appendectomy. Prior to surgery, it is important that patients receive adequate IV fluids in order to correct dehydration that commonly develops as a result of fever and vomiting in patients with appendicitis. Patients should also be started on antibiotics (such as a second-generation cephalosporin). Most surgeons will perform a laparoscopic appendectomy, which may have some advantage over removing the appendix through a single larger incision. During the laparoscopic appendectomy, a small incision is made at the umbilicus, and two additional incisions are made in the lower abdomen. The appendix is typically delivered through the umbilicus, and all incisions are then closed with dissolvable sutures. If the appendix is not ruptured, the patient may start drinking liquids shortly after waking up from the operation and may be advanced to a solid diet the next day. In general, the same steps are taken when appendectomy is performed through an open approach. The most common complication after appendectomy is a surgical site infection. Other risks, including bleeding or damage to other structures inside the abdomen, are extremely rare. Recovery from surgery is dependent on the individual patient. Most children are back to school approximately 1 week after surgery and usually are allowed to return to full physical activity after 2 to 3 weeks. During the recovery period, over-the-counter pain medication may be required. Older patients tend to require a longer time for full recovery.
Management of the Child with Perforated Appendicitis
The signs and symptoms of perforated appendicitis can closely mimic those of gastroenteritis and include abdominal pain, vomiting, and diarrhea. Alternatively, the child may present with symptoms of intestinal obstruction. An abdominal mass may be present in the lower abdomen. When the symptoms have been present for more than 4 or 5 days and an abscess is suspected, it is reasonable to obtain a CT of the abdomen and pelvis with IV, oral, and rectal contrast to visualize the appendix and the presence of an associated abscess, phlegmon, or fecalith (Fig. 39-21).
Computed tomography scan of the abdomen showing the presence of a ruptured appendix with pelvic fluid and a fecalith (arrow).
An individualized approach is necessary for the child who presents with perforated appendicitis. When there is evidence of generalized peritonitis, intestinal obstruction, or systemic toxicity, the child should undergo appendectomy. This should be delayed only for as long as is required to ensure adequate fluid resuscitation and administration of broad-spectrum antibiotics. The operation can be performed through an open or laparoscopic approach. One distinct advantage of the laparoscopic approach is that it provides excellent visualization of the pelvis and all four quadrants of the abdomen. At the time of surgery, adhesions are gently lysed, abscess cavities are drained, and the appendix is removed. Drains are seldom used, and the skin incisions can be closed primarily. If a fecalith is identified outside the appendix on CT, every effort should be made to retrieve it and to remove it along with the appendix, if at all possible. Often, the child in whom symptoms have been present for more than 4 or 5 days will present with an abscess without evidence of generalized peritonitis. Under these circumstances, it is appropriate to perform image-guided percutaneous drainage of the abscess followed by broad-spectrum antibiotic therapy. The inflammation will generally subside within several days, and the appendix can be safely removed as an outpatient 6 to 8 weeks later. If the child's symptoms do not improve or if the abscess is not amenable to percutaneous drainage, then laparoscopic or open appendectomy and abscess drainage is required. Patients who present with a phlegmon in the region of a perforated appendix may be managed in a similar manner. In general, children who are younger than 4 or 5 years of age do not respond as well to initial nonoperative approach because their bodies do not localize or isolate the inflammatory process. Thus, these patients are more likely to require early surgical intervention. Patients who have had symptoms of appendicitis for no more than 4 days should probably undergo "early" appendectomy, since the inflammatory response is not as excessive during that initial period and the procedure can be performed safely.
Other Causes of Abdominal Pain That Mimic Appendicitis in Children
As mentioned earlier, appendicitis can be one of the most difficult diagnoses to establish in children with abdominal pain, in part because of the large number of diseases that present in a similar fashion. Patients with urinary tract infection can present very similar to those with appendicitis. However, patients with urinary tract infection are less likely to present with vomiting and are likely to also experience difficulty with urination, characterized by pressure, burning, and frequency. Constipation may be commonly confused with appendicitis in its earliest stages. However, patients with constipation rarely have fever and will not have abnormalities in their blood work. Ovarian torsion can mimic appendicitis, given the severe abdominal pain that accompanies this condition. However, patients with ovarian torsion are generally asymptomatic until the acute onset of severe pain. By contrast, patients with appendicitis generally experience gradual onset of pain associated with nausea and vomiting. Finally, children and young adults are always at risk for the development of gastroenteritis. However, unlike appendicitis, patients with gastroenteritis generally present with persistent vomiting and occasionally diarrhea, which precedes the onset of the abdominal pain.
Intestinal Duplications
Duplications represent mucosa-lined structures that are in continuity with the gastrointestinal tract. Although they can occur at any level in the gastrointestinal tract, duplications are found most commonly in the ileum within the leaves of the mesentery. Duplications may be long and tubular, but usually, they are cystic masses. In all cases, they share a common wall with the intestine. Symptoms associated with enteric duplication cysts include recurrent abdominal pain, emesis from intestinal obstruction, or hematochezia. Such bleeding typically results from ulceration in the duplication or in the adjacent intestine if the duplication contains ectopic gastric mucosa. On examination, a palpable mass is often identified. Children may also develop intestinal obstruction. Torsion may produce gangrene and perforation.
The ability to make a preoperative diagnosis of enteric duplication cyst usually depends on the presentation. CT, US, and technetium pertechnetate scanning can be very helpful. Occasionally, a duplication can be seen on small bowel follow-through or barium enema. In the case of short duplications, resection of the cyst and adjacent intestine with end-to-end anastomosis can be performed. If resection of long duplications would compromise intestinal length, multiple enterotomies and mucosal stripping in the duplicated segment will allow the walls to collapse and become adherent. An alternative method is to divide the common wall using the GIA stapler, forming a common lumen. Patients with duplications who undergo complete excision without compromise of the length of remaining intestine have an excellent prognosis.
Meckel's Diverticulum
A Meckel's diverticulum is a remnant of a portion of the embryonic omphalomesenteric (vitelline) duct. It is located on the antimesenteric border of the ileum, usually within 2 ft of the ileocecal valve (Fig. 39-22). It may be found incidentally at surgery or may present with inflammation masquerading as appendicitis. Perforation of a Meckel's diverticulum may occur if the outpouching becomes impacted with food, leading to distention and necrosis. Occasionally, bands of tissue extend from the Meckel's diverticulum to the anterior abdominal wall, and these may represent lead points around which internal hernias may develop. This is an important cause of intestinal obstruction in the older child who has a scarless abdomen. Similar to duplications, ectopic gastric mucosa may produce ileal ulcerations that bleed and lead to the passage of maroon-colored stools. Pancreatic mucosa may also be present. Diagnosis may be made by technetium pertechnetate scans when the patient presents with bleeding. Treatment is surgical. If the base is narrow and there is no mass present in the lumen of the diverticulum, a wedge resection of the diverticulum with transverse closure of the ileum can be performed. A linear stapler is especially useful in this circumstance. When a mass of ectopic tissue is palpable, if the base is wide, or when there is inflammation, it is preferable to perform a resection of the involved bowel and end-to-end ileoileostomy.
Operative photograph showing the presence of a Meckel's diverticulum (arrow).
Mesenteric Cysts
Mesenteric cysts are similar to duplications in their location within the mesentery. However, they do not contain any mucosa or muscular wall. Chylous cysts may result from congenital lymphatic obstruction. Mesenteric cysts can cause intestinal obstruction or may present as an abdominal mass. The diagnosis may be made by abdominal US or CT. Treatment involves surgical excision. This may require resection of the adjacent intestine, particularly for extensive, multicystic lesions. In cases where complete excision is not possible due to the close proximity to vital structures, partial excision or marsupialization should be performed.
Hirschsprung's Disease
In his classic textbook entitled Pediatric Surgery, Dr. Orvar Swenson, who is eponymously associated with one of the classic surgical treatments for Hirschsprung's disease, described this condition as follows: "Congenital megacolon is caused by a malformation in the pelvic parasympathetic system which results in the absence of ganglion cells in Auerbach's plexus of a segment of distal colon. Not only is there an absence of ganglion cells, but the nerve fibers are large and excessive in number, indicating that the anomaly may be more extensive than the absence of ganglion cells." This narrative of Hirschsprung's disease is as accurate today as it was more than 50 years ago and summarizes the essential pathologic features of this disease: absence of ganglion cells in Auerbach's plexus and hypertrophy of associated nerve trunks. The cause of Hirschsprung's disease remains incompletely understood, although current thinking suggests that the disease results from a defect in the migration of neural crest cells, which are the embryonic precursors of the intestinal ganglion cell. Under normal conditions, the neural crest cells migrate into the intestine from cephalad to caudad. The process is completed by the twelfth week of gestation, but the migration from midtransverse colon to anus takes 4 weeks. During this latter period, the fetus is most vulnerable to defects in migration of neural crest cells. This may explain why most cases of aganglionosis involve the rectum and rectosigmoid. The length of the aganglionic segment of bowel is therefore determined by the most distal region that the migrating neural crest cells reach. In rare instances, total colonic aganglionosis may occur.
Recent studies have shed light on the molecular basis for Hirschsprung's disease. Patients with Hirschsprung's disease have an increased frequency of mutations in several genes, including GDNF, its receptor Ret, or its coreceptor Gfra-1. Moreover, mutations in these genes also lead to aganglionic megacolon in mice, which provides the opportunity to study the function of the encoded proteins. Initial investigations indicate that GDNF promotes the survival, proliferation, and migration of mixed populations of neural crest cells in culture. Other studies have revealed that GDNF is expressed in the gut in advance of migrating neural crest cells and is chemoattractive for neural crest cells in culture. These findings raise the possibility that mutations in the GDNF or Ret genes could lead to impaired neural crest migration in utero and the development of Hirschsprung's disease.
The incidence of sporadic Hirschsprung's disease is 1 in 5000 live births. There are reports of increased frequency of Hirschsprung's disease in multiple generations of the same family. Occasionally such families have mutations in the genes described earlier, including the Ret gene. Because the aganglionic colon does not permit normal peristalsis to occur, the presentation of children with Hirschsprung's disease is characterized by a functional distal intestinal obstruction. In the newborn period, the most common symptoms are abdominal distention, failure to pass meconium, and bilious emesis. Any infant who does not pass meconium beyond 48 hours of life must be investigated for the presence of Hirschsprung's disease. Occasionally, infants present with a dramatic complication of Hirschsprung's disease called enterocolitis. This pattern of presentation is characterized by abdominal distention and tenderness and is associated with manifestations of systemic toxicity that include fever, failure to thrive, and lethargy. Infants are often dehydrated and demonstrate a leukocytosis or increase in circulating band forms on hematologic evaluation. On rectal examination, forceful expulsion of foul-smelling liquid feces is typically observed and represents the accumulation of stool under pressure in an obstructed distal colon. Treatment includes rehydration, systemic antibiotics, nasogastric decompression, and rectal irrigations while the diagnosis of Hirschsprung's disease is being confirmed. In children who do not respond to nonoperative management, a decompressive stoma is required. It is important to ensure that this stoma is placed in ganglion-containing bowel, which must be confirmed by frozen section at the time of stoma creation.
In approximately 20% of cases, the diagnosis of Hirschsprung's disease is made beyond the newborn period. These children have severe constipation, which has usually been treated with laxatives and enemas. Abdominal distention and failure to thrive may also be present at diagnosis.
The definitive diagnosis of Hirschsprung's disease is made by rectal biopsy. Samples of mucosa and submucosa are obtained at 1, 2, and 3 cm from the dentate line. This can be performed at the bedside in the neonatal period without anesthesia, as samples are taken in bowel that does not have somatic innervation and is thus not painful to the child. In older children, the procedure should be performed using IV sedation. The histopathology of Hirschsprung's disease is the absence of ganglion cells in the myenteric plexuses, increased acetylcholinesterase staining, and the presence of hypertrophied nerve bundles.
It is important to obtain a barium enema in children in whom the diagnosis of Hirschsprung's disease is suspected. This test may demonstrate the location of the transition zone between the dilated ganglionic colon and the distal constricted aganglionic rectal segment. Our practice is to obtain this test before instituting rectal irrigations if possible, so that the difference in size between the proximal and distal bowel is preserved. Although the barium enema can only suggest, but not reliably establish, the diagnosis of Hirschsprung's disease, it is very useful in excluding other causes of distal intestinal obstruction. These include small left colon syndrome (as occurs in infants of diabetic mothers), colonic atresia, meconium plug syndrome, or the unused colon observed in infants after the administration of magnesium or tocolytic agents. The barium enema in total colonic aganglionosis may show a markedly shortened colon. Some surgeons have found the use of rectal manometry helpful, particularly in older children, although it is relatively inaccurate.
The diagnosis of Hirschsprung's disease requires surgery in all cases. The classic surgical approach consisted of a multiple-stage procedure. This included a colostomy in the newborn period, followed by a definitive pull-through operation after the child was over 10 kg. There are three viable options for the definitive pull-through procedure that are currently used. Although individual surgeons may advocate one procedure over another, studies have demonstrated that the outcome after each type of operation is similar. For each of the operations that is performed, the principles of treatment include confirming the location in the bowel where the transition zone between ganglionic and aganglionic bowel exists, resecting the aganglionic segment of bowel, and performing an anastomosis of ganglionated bowel to either the anus or a cuff of rectal mucosa (Fig. 39-23).
The three operations for surgical correction of Hirschsprung's disease. A. The Duhamel procedure leaves the rectum in place and brings ganglionic bowel into the retrorectal space. B. The Swenson procedure is a resection with end-to-end anastomosis performed by exteriorizing bowel ends through the anus. C. The Soave operation is performed by endorectal dissection and removal of mucosa from the aganglionic distal segment and bringing the ganglionic bowel down to the anus within the seromuscular tunnel.
It is now well established that a primary pull-through procedure can be performed safely, even in the newborn period. This approach follows the same treatment principles as a staged procedure and saves the patient from an additional surgical procedure. Many surgeons perform the intra-abdominal dissection using the laparoscope. This approach is especially useful in the newborn period, as this provides excellent visualization of the pelvis. In children with significant colonic distention, it is important to allow for a period of decompression using a rectal tube if a single-staged pull-through is to be performed. In older children with very distended, hypertrophied colon, it may be prudent to perform a colostomy to allow the bowel to decompress, prior to performing a pull-through procedure. However, it should be emphasized that there is no upper age limit for performing a primary pull-through.
Of the three pull-through procedures performed for Hirschsprung's disease, the first is the original Swenson procedure. In this operation, the aganglionic rectum is dissected in the pelvis and removed down to the anus. The ganglionic colon is then anastomosed to the anus via a perineal approach. In the Duhamel procedure, dissection outside the rectum is confined to the retrorectal space, and the ganglionic colon is anastomosed posteriorly just above the anus. The anterior wall of the ganglionic colon and the posterior wall of the aganglionic rectum are anastomosed using a stapler. Although both of these procedures are extremely effective, they are limited by the possibility of damage to the parasympathetic nerves that are adjacent to the rectum. To circumvent this potential problem, the Soave procedure involves dissection entirely within the rectum. The rectal mucosa is stripped from the muscular sleeve, and the ganglionic colon is brought through this sleeve and anastomosed to the anus. This operation may be performed completely from below. In all cases, it is critical that the level at which ganglionated bowel exists be determined. Most surgeons believe that the anastomosis should be performed at least 5 cm from the point at which ganglion cells are found. This avoids performing a pull-through in the transition zone, which is associated with a high incidence of complications due to inadequate emptying of the pull-through segment. Up to one third of patients who undergo a transition zone pull-through will require a reoperation.
The main complications of all of the procedures include postoperative enterocolitis, constipation, and anastomotic stricture. As mentioned, long-term results with the three procedures are comparable and generally excellent in experienced hands. These three procedures also can be adapted for total colonic aganglionosis in which the ileum is used for the pull-through segment.
Anorectal Malformations
Anatomic Description
Anorectal malformations describe a spectrum of congenital anomalies that include imperforate anus and persistent cloaca. Anorectal malformations occur in approximately 1 in 5000 live births and affect males and females almost equally. The embryologic basis includes failure of descent of the urorectal septum. The level to which this septum descends determines the type of anomaly that is present, which subsequently influences the surgical approach.
In patients with imperforate anus, the rectum fails to descend through the external sphincter complex. Instead, the rectal pouch ends "blindly" in the pelvis, above or below the levator ani muscle. In most cases, the blind rectal pouch communicates more distally with the genitourinary system or with the perineum through a fistulous tract. Traditionally, anatomic description of imperforate anus has been characterized as either "high" or "low" depending on whether the rectum ends above the levator ani muscle complex or partially descends through this muscle (Fig. 39-24). Based on this classification system, in male patients with high imperforate anus, the rectum usually ends as a fistula into the membranous urethra. In females, high imperforate anus often occurs in the context of a persistent cloaca. In both males and females, low lesions are associated with a fistula to the perineum. In males, the fistula connects with the median raphe of the scrotum or penis. In females, the fistula may end within the vestibule of the vagina, which is located immediately outside the hymen or at the perineum.
Low imperforate anus in a male. Note the well-developed buttocks. The perineal fistula was found at the midline raphe.
Because this classification system is somewhat arbitrary, Peña proposed a classification system that specifically and unambiguously describes the location of the fistulous opening. In males, the fistula may communicate with: (a) the perineum (cutaneous perineal fistula); (b) the lowest portion of the posterior urethra (rectourethral bulbar fistula); (c) the upper portion of the posterior urethra (rectourethral prostatic fistula); or (d) the bladder neck (rectovesicular fistula). In females, the fistula may open to the perineum between the female genitalia and the center of the sphincter (cutaneous perineal fistula) or into the vestibule of the vagina (vestibular fistula) (Fig. 39-25). In both sexes, the rectum may end in a completely blind fashion (imperforate anus without fistula). In rare cases, patients may have a normal anal canal, yet there may be total atresia or severe stenosis of the rectum.
Imperforate anus in a female. A catheter has been placed into the fistula, which is in the vestibule of the vagina.
The most frequent defect in males is imperforate anus with rectourethral fistula, followed by rectoperineal fistula then rectovesical or rectobladder neck fistula. In females, the most frequent defect is the rectovestibular fistula, followed by the cutaneous perineal fistula. The third most common defect in females is the persistent cloaca. This lesion represents a wide spectrum of malformations in which the rectum, vagina, and urinary tract meet and fuse into a single common channel. On physical examination, a single perineal orifice is observed and is located at the place where the urethra normally opens. Typically, the external genitalia are hypoplastic.
Associated Malformations
Approximately 60% of patients have an associated malformation. The most common is a urinary tract defect, which occurs in approximately 50% of patients. Skeletal defects are also seen, and the sacrum is most commonly involved. Spinal cord anomalies, especially tethered cored, are common, particularly in children with high lesions. Gastrointestinal anomalies occur, most commonly EA. Cardiac anomalies may be noted, and occasionally patients present with a constellation of defects as part of the VACTERLL syndrome (described earlier).
Management of Patients with Imperforate Anus
Patients with imperforate anus are usually stable, and the diagnosis is readily apparent. Despite the obstruction, the abdomen is initially not distended, and there is rarely any urgency to intervene. The principles of management center around diagnosing the type of defect that is present (high vs. low) and evaluating the presence of associated anomalies. It may take up to 24 hours before the presence of a fistula on the skin is noted, and thus it is important to observe the neonate for some period before definitive surgery is undertaken. All patients should therefore have an orogastric tube placed and be monitored for the appearance of meconium in or around the perineum or in the urine. Investigation for associated defects should include an US of the abdomen to assess for the presence of urinary tract anomaly. Other tests should include an echocardiogram and spinal radiographs. A US of the spine should be performed to look for the presence of a tethered cord. To further classify the location of the fistula as either "high" vs. "low," a lateral abdominal radiograph can be obtained with a radiopaque marker on the perineum. By placing the infant in the inverted position, the distance between the most distal extent of air in the rectum and the perineal surface can be measured. This study is imprecise, however, and may add little to the overall management of these patients.
The surgical management of infants with imperforate anus is determined by the anatomic defect. In general, when a low lesion is present, only a perineal operation is required without a colostomy. Infants with a high lesion require a colostomy in the newborn period, followed by a pull-through procedure at approximately 2 months of age. When a persistent cloaca is present, the urinary tract needs to be carefully evaluated at the time of colostomy formation to ensure that normal emptying can occur and to determine whether the bladder needs to be drained by means of a vesicostomy. If there is any doubt about the type of lesion, it is safer to perform a colostomy rather than jeopardize the infant's long-term chances for continence by an injudicious perineal operation.
The type of pull-through procedure favored by most pediatric surgeons today is the posterior sagittal anorectoplasty (PSARP) procedure, as described by Peña and DeVries. This involves placing the patient in the prone jackknife position, dividing the levator ani and external sphincter complex in the midline posteriorly, dividing the communication between the gastrointestinal tract and the urinary tract, and bringing down the rectum after sufficient length is achieved. The muscles are then reconstructed and sutured to the rectum. The outcome of 1192 patients who had undergone this procedure has been reviewed by Peña and Hong. Seventy-five percent of patients were found to have voluntary bowel movements, and nearly 40% were considered totally continent. As a rule, patients with high lesions demonstrate an increased incidence of incontinence, whereas those with low lesions are more likely to be constipated. Management of patients with high imperforate anus can be greatly facilitated using a laparoscopic-assisted approach, in which the patient is operated on in the supine position, and the rectum is mobilized down to the fistulous connection to the bladder neck. This fistulous connection is then divided, and the rectum is completely mobilized down to below the peritoneal reflection. The operation then proceeds at the perineum, and the location of the muscle complex is determined using the nerve stimulator. A Veress needle is then advanced through the skin at the indicated site, with the laparoscope providing guidance to the exact intrapelvic orientation. Dilators are then placed over the Veress needle, the rectum is pulled through this peritoneal opening, and an anoplasty is performed.
The Approach to the Jaundiced Infant
Jaundice is present during the first week of life in 60% of term infants and 80% of preterm infants. There is usually accumulation of unconjugated bilirubin, but there may also be deposition of direct bilirubin. During fetal life, the placenta is the principal route of elimination of unconjugated bilirubin. In the newborn infant, bilirubin is conjugated through the activity of glucoronyl transferase. In the conjugated form, bilirubin is water soluble, which results in its excretion into the biliary system and then into the gastrointestinal tract. Newborns have a relatively high level of circulating hemoglobin and relative immaturity of the conjugating machinery. This results in a transient accumulation of bilirubin in the tissues, which is manifested as jaundice. Physiologic jaundice is evident by the second or third day of life and usually resolves within approximately 5 to 7 days. By definition, jaundice that persists beyond 2 weeks is considered pathologic.
Pathologic jaundice may be due to biliary obstruction, increased hemoglobin load, or liver dysfunction. The workup of the jaundiced infant therefore should include a search for the following possibilities: (a) obstructive disorders, including biliary atresia, choledochal cyst, and inspissated bile syndrome; (b) hematologic disorders, including ABO incompatibility, Rh incompatibility, and spherocytosis; (c) metabolic disorders, including α1-antitrypsin deficiency, galactosemia, and pyruvate kinase deficiency; and (d) congenital infection, including syphilis and rubella.
Biliary Atresia
Biliary atresia is a rare disease associated with significant morbidity and mortality. This disease is characterized by a fibroproliferative obliteration of the biliary tree, which progresses toward hepatic fibrosis, cirrhosis, and end-stage liver failure. The incidence of this disease is approximately 1 in 8000 to 1 in 18,000. The etiology of biliary atresia is likely multifactorial. In the classic textbook Abdominal Surgery of Infancy and Childhood, Ladd and Gross described the cause of biliary atresia as an "arrest of development during the solid stage of bile duct formation." Previously proposed theories on the etiology of biliary atresia have focused on defects in hepatogenesis, prenatal vasculogenesis, immune dysregulation, infectious agents, and exposure to toxins. More recently, genetic mutations in the cfc1 gene, implicated in left-right axis determinations, were identified in patients with biliary atresia-splenic malformation syndrome. Additionally, the detection of a higher incidence of maternal microchimerism in the livers of males with biliary atresia has led to the suggestion that consequent expression of maternal antigens may lead to an autoimmune process leading to inflammation and obliteration of the biliary tree. Recent animal studies strongly implicate perinatal exposure to reovirus or rotavirus. Such viral exposure may lead to periportal inflammation mediated by interferon-γ and other cytokines.
Infants with biliary atresia present with jaundice at birth or shortly thereafter. The diagnosis of biliary atresia is frequently not entertained by pediatricians in part because physiologic jaundice of the newborn is so common and biliary atresia is so uncommon. As such, it is not unusual for there to be a delay in diagnosis. However, infants with biliary atresia characteristically have acholic, pale gray–appearing stools, secondary to obstructed bile flow. With further passage of time, these infants manifest progressive failure to thrive, and if untreated, they develop stigmata of liver failure and portal hypertension, particularly splenomegaly and esophageal varices.
The obliterative process of biliary atresia involves the common duct, cystic duct, one or both hepatic ducts, and the gallbladder, in a variety of combinations. The histopathology of patients with biliary atresia includes inflammatory changes within the parenchyma of the liver, as well as fibrous deposition at the portal plates that is observed on trichrome staining of frozen tissue sections. In certain cases, bile duct proliferation may be seen, a relatively nonspecific marker of liver injury. Approximately 25% of patients with biliary atresia have coincidental malformations, often associated with polysplenia and which may include intestinal malrotation, preduodenal portal vein, and intrahepatic vena cava.
In general, the diagnosis of biliary atresia is made using a combination of studies, as no single test is sufficiently sensitive or specific. Fractionation of the serum bilirubin is performed to determine if the associated hyperbilirubinemia is conjugated or unconjugated. Workup commonly includes the analysis of TORCH infection titers as well as viral hepatitis. Typically, US is performed to assess the presence of other causes of biliary tract obstruction including choledochal cyst. The absence of a gallbladder is highly suggestive of the diagnosis of biliary atresia. However, the presence of a gallbladder does not exclude the diagnosis of biliary atresia because in approximately 10% of biliary atresia patients, the distal biliary tract is patent and a gallbladder may be visualized, even though the proximal ducts are atretic. It is important to note that the intrahepatic bile ducts are never dilated in patients with biliary atresia. In many centers, a nuclear medicine scan using technetium-99m iminodiacetic acid, performed after pretreatment of the patient with phenobarbital, has proven to be an accurate and reliable study. If radionuclide appears in the intestine, there is patency of the biliary tree and the diagnosis of biliary atresia is excluded. If radionuclide is concentrated by the liver but not excreted despite treatment with phenobarbital and the metabolic screen, particularly α1-antitrypsin determination, is normal, the presumptive diagnosis is biliary atresia. A percutaneous liver biopsy might potentially distinguish between biliary atresia and other sources of jaundice such as neonatal hepatitis. When these tests point to or cannot exclude the diagnosis of biliary atresia, surgical exploration is warranted. At surgery, a cholangiogram may be performed if possible, using the gallbladder as a point of access. This may be performed using a laparoscope. The cholangiogram demonstrates the anatomy of the biliary tree, determines whether extrahepatic bile duct atresia is present, and evaluates whether there is distal bile flow into the duodenum. The cholangiogram may demonstrate hypoplasia of the extrahepatic biliary system. This condition is associated with hepatic parenchymal disorders that cause severe intrahepatic cholestasis, including α1-antitrypsin deficiency and biliary hypoplasia (Alagille's syndrome). Alternatively, a cursory assessment of the extrahepatic biliary tree may clearly delineate the atresia.
Inspissated Bile Syndrome
This term is applied to patients with normal biliary tracts who have persistent obstructive jaundice. Increased viscosity of bile and obstruction of the canaliculi are implicated as causes. The condition has been seen in infants receiving parenteral nutrition, but it is also encountered in conditions associated with hemolysis or in cystic fibrosis. In some instances, no etiologic factors can be defined. Neonatal hepatitis may present in a similar fashion to biliary atresia. This disease is characterized by persistent jaundice due to acquired biliary inflammation without obliteration of the bile ducts. There may be a viral etiology, and the disease is usually self-limited. In this case, cholangiography is both diagnostic and therapeutic.
If the diagnosis of biliary atresia is confirmed intraoperatively, then surgical treatment is undertaken at the same setting. Currently, first-line therapy consists of creation of a hepatoportoenterostomy, as described by Kasai. The purpose of this procedure is to promote bile flow into the intestine. The procedure is based on Kasai's observation that the fibrous tissue at the porta hepatis invests microscopically patent biliary ductules that, in turn, communicate with the intrahepatic ductal system (Fig. 39-26). Transecting this fibrous tissue at the portal plate, invariably encountered cephalad to the bifurcating portal vein, opens these channels and establishes bile flow into a surgically constructed intestinal conduit, usually a Roux-en-Y limb of jejunum (Fig. 39-27). Some authors believe that an intussuscepted antireflux valve is useful in preventing retrograde bile reflux, although the data suggest that it does not impact outcome. A liver biopsy is performed at the time of surgery to determine the degree of hepatic fibrosis that is present. The diameter of bile ducts at the portal plate is predictive of likelihood of long-term success of biliary drainage through the portoenterostomy. Numerous studies also suggest that the likelihood of surgical success is inversely related to the age at the time of portoenterostomy. Infants treated prior to 60 days of life are more likely to achieve successful and long-term biliary drainage than older infants. Although the outlook is less favorable for patients after the twelfth week, it is reasonable to proceed with surgery even beyond this time point, as the alternative is certain liver failure. It is noteworthy that a significant number of patients have had favorable outcomes after undergoing portoenterostomy despite advanced age at time of diagnosis.
Operative photograph showing Kasai portoenterostomy. Arrows denote site of the anastomosis. Note the engorged liver.
Schematic illustration of the Kasai portoenterostomy for biliary atresia. An isolated limb of jejunum is brought to the porta hepatis and anastomosed to the transected ducts at the liver plate.
Bile drainage is anticipated when the operation is carried out early; however, bile flow does not necessarily imply cure. Approximately one third of patients remain symptom free after portoenterostomy; the remainder require liver transplantation due to progressive liver failure. Independent risk factors that predict failure of the procedure include bridging liver fibrosis at the time of surgery and postoperative cholangitic episodes. A review of the data of the Japanese Biliary Atresia Registry (JBAR), which includes the results of 1381 patients, showed that the 10-year survival rate was 53% without transplantation and 66.7% with transplantation. A common postoperative complication is cholangitis. There is no effective strategy to completely eliminate this complication, and the effectiveness of long-term prophylactic antibiotics has not been fully resolved. The Childhood Liver Research and Education Network (ChiLDREN, formerly the Biliary Atresia Research Consortium) is an active consortium of 15 children's hospitals in the United States, funded by the National Institutes of Health (NIH), which studies rare cholestatic liver diseases of infants and children (http://childrennetwork.org/). The primary disease of research interest is biliary atresia, as four of the seven active studies are dedicated to biliary atresia. Two of these four biliary atresia studies are therapeutic trials. Currently, enrollment for an NIH-funded, randomized, double-blind, placebo-controlled trial designed to determine if adjuvant steroids improves outcome of infants undergoing Kasai portoenterostomy has been completed. Treatment arms will be unblended, and outcomes of patients in this trial in terms of successful biliary drainage and survival with patients' native livers will be determined. Additionally, ChiLDREN is about to embark on a phase I trial looking at the safety and efficacy of adjuvant IV immunoglobulin (IVIg) given to infants with biliary atresia following Kasai portoenterostomy.
From this consortium, Superina and colleagues recently reported on the prospectively collected clinical, surgical, and outcomes data on 244 patients with biliary atresia. Notably, over 80% of infants manifested Ohi type III variant (atresia of the porta hepatis) compared with 10% with Ohi type I (atresia of the common bile duct) or 7% with Ohi type II (atresia of the hepatic duct). Outcomes analysis revealed a significantly greater survival with one's native liver for infants with type I compared with those with type II or III. Moreover, infants with Ohi distal subtype a (patent common bile duct) had significantly improved survival compared to those with Ohi distal subtypes b, c, or d (nonpatent common bile duct). Improved survival with the child's native liver was also observed in this study in patients less than 75 days old at time of Kasai portoenterostomy, no ascites at exploration, nonnodular liver, and low fibrosis score. Importantly, clearance of jaundice as defined by achieving a total bilirubin of less than 2 mg/dL within 3 months after portoenterostomy was highly predictive of survival with the native liver. The effect of hospital volume was not the focus of this publication. However, Davenport and colleagues recently reported on their experience in the United Kingdom where surgical care of infants with biliary atresia has been centralized to three hospitals. The authors report successful clearance of jaundice in 55% of patients, which is considerably better than clearance rates reported from the United States, France, or Switzerland and comparable to clearance rates reported from Taiwan where there is centralization of care.
Improved survival with one's native liver following Kasai portoenterostomy has previously been noted by numerous authors, as in the ChiLDREN consortium. Tseng and colleagues reported on improved rates of early diagnosis of biliary atresia (<60 days of age) following implementation of a national screening program for infant stool color in Taiwan. Given that early diagnosis of biliary atresia is associated with greater success of bile drainage, the authors reasonably speculate that higher rates of early diagnosis of biliary atresia nationally will translate into improved outcomes following the Kasai procedure.
Previous authors have published merits of revising the portoenterostomy in select patients if drainage of bile stops. Recently, Bondoc and colleagues reported on their experience with revision of portoenterostomies. Specifically, the authors reported on 183 patients who underwent Kasai portoenterostomy for biliary atresia, of whom 24 underwent revision for recurrence of nondrainage after successful bypass. Of the patients who underwent revision for nondrainage, 75% ultimately again achieved drainage after the second procedure, of whom nearly 50% survived long term with their native livers. The authors conclude that in selected patients in whom bile flow was established following the Kasai procedure and who then lost that flow, revision of the portoenterostomy is a reasonable treatment option with good success.
Choledochal Cyst
The term choledochal cyst refers to a spectrum of congenital biliary tract disorders that were previously grouped under the name idiopathic dilation of the common bile duct. After the classification system proposed by Alonso-Lej, five types of choledochal cyst are described. Type I cyst is characterized by fusiform dilatation of the bile duct. This is the most common type and is found in 80% to 90% of cases. A type II choledochal cyst appears as an isolated diverticulum protruding from the wall of the common bile duct. The cyst may be joined to the common bile duct by a narrow stalk. Type III choledochal cysts arise from the intraduodenal portion of the common bile duct and are also known as choledochoceles. Type IVA cysts consist of multiple dilatations of the intrahepatic and extrahepatic bile ducts. Type IVB choledochal cysts are multiple dilatations involving only the extrahepatic bile ducts. Type V (Caroli's disease) consists of multiple dilatations limited to the intrahepatic bile ducts.
Choledochal cyst is most appropriately considered the predominant feature in a constellation of pathologic abnormalities that can occur within the pancreato-biliary system. Frequently associated with choledochal cyst is an anomalous junction of the pancreatic and common bile ducts. The etiology of choledochal cyst is controversial. Babbit proposed an abnormal pancreatic and biliary duct junction, with the formation of a "common channel" into which pancreatic enzymes are secreted. This process results in weakening of the bile duct wall by gradual enzymatic destruction, leading to dilatation, inflammation, and finally cyst formation. Not all patients with choledochal cyst demonstrate an anatomic common channel, which raises questions regarding the accuracy of this model.
Choledochal cyst is more common in females than in males (4:1). Typically these present in children beyond the toddler age group. The classic symptom triad consists of abdominal pain, mass, and jaundice. However, this complex is actually encountered in fewer than half of the patients. The more usual presentation is that of episodic abdominal pain, often recurring over the course of months or years and generally associated with only minimal jaundice that may escape detection. If left undiagnosed, patients may develop cholangitis or pancreatitis. Cholangitis may lead to the development of cirrhosis and portal hypertension. Choledochal cyst can present in the newborn period, where the symptoms are very similar to those of biliary atresia. Often neonates will have an abdominal mass at presentation.
Choledochal cyst is frequently diagnosed in the fetus at a screening prenatal US. In the older child or adolescent, abdominal ultrasonography may reveal a cystic structure arising from the biliary tree. CT will confirm the diagnosis. These studies will demonstrate the dimensions of the cyst and define its relationship to the vascular structures in the porta hepatis, as well as the intrahepatic ductal configuration. Endoscopic retrograde cholangiopancreatography (ERCP) is reserved for patients in whom confusion remains after evaluation by less invasive imaging modalities. Magnetic resonance cholangiopancreatography may provide a more detailed depiction of the anatomy of the cyst and its relationship to the bifurcation of the hepatic ducts and into the pancreas.
The cyst wall is composed of fibrous tissue and is devoid of mucosal lining. As a result, the treatment of choledochal cyst is surgical excision followed by biliary-enteric reconstruction. There is no role for internal drainage by cystoenterostomy, which leaves the cyst wall intact and leads to the inevitable development of cholangitis. Rarely, choledochal cyst can lead to the development of a biliary tract malignancy. This provides a further rationale for complete cyst excision.
Resection of the cyst requires circumferential dissection. The posterior plane between the cyst and portal vein must be carefully dissected to accomplish removal. The pancreatic duct, which may enter the distal cyst, is vulnerable to injury during distal cyst excision but can be avoided by avoiding entry into the pancreatic parenchyma. In cases where the degree of pericystic inflammation is dense, it may be unsafe to attempt complete cyst removal. In this instance, it is reasonable to dissect within the posterior wall of the cyst, which allows the inner lining of the back wall to be dissected free from the outer layer that directly overlies the portal vascular structures. The lateral and anterior cyst, as well as the internal aspect of the back wall, is removed, yet the outer posterior wall remains behind. Cyst excision is accomplished, and the proximal bile duct is anastomosed to the intestinal tract typically via a Roux-en Y jejunal limb. More recently, laparoscopic-assisted resections of choledochal cysts have been described. In these cases, the end-to-side jejunojejunostomy is performed extracorporeally, but the remainder of the procedure is completed using minimally invasive techniques.
The prognosis for children who have undergone complete excision of choledochal cyst is excellent. Complications include anastomotic stricture, cholangitis, and intrahepatic stone formation. These complications may develop a long time after surgery has been completed.
Embryology of the Abdominal Wall
The abdominal wall is formed by four separate embryologic folds: cephalic, caudal, right, and left lateral folds. Each of these is composed of somatic and splanchnic layers and develops toward the anterior center portion of the coelomic cavity, joining to form a large umbilical ring that surrounds the two umbilical arteries, the vein, and the yolk sac or omphalomesenteric duct. These structures are covered by an outer layer of amnion, and the entire unit composes the umbilical cord. Between the fifth and tenth weeks of fetal development, the intestinal tract undergoes rapid growth outside the abdominal cavity within the proximal portion of the umbilical cord. As development is completed, the intestine gradually returns to the abdominal cavity. Contraction of the umbilical ring completes the process of abdominal wall formation.
Failure of the cephalic fold to close results in sternal defects such as congenital absence of the sternum. Failure of the caudal fold to close results in exstrophy of the bladder and, in more extreme cases, exstrophy of the cloaca. Interruption of central migration of the lateral folds results in omphalocele. Gastroschisis, originally thought to be a variant of omphalocele, possibly results from a fetal accident in the form of intrauterine rupture of a hernia of the umbilical cord, although other hypotheses have been advanced.
Failure of the umbilical ring to close results in a central defect in the linea alba. The resulting umbilical hernia is covered by normal umbilical skin and subcutaneous tissue, but the fascial defect allows protrusion of abdominal contents. Hernias less than a centimeter in size at the time of birth usually will close spontaneously by 4 to 5 years of life and, in most cases, should not undergo early repair. Sometimes the hernia is large enough that the protrusion is disfiguring and disturbing to both the child and the family. In such circumstances, early repair may be advisable (Fig. 39-28).
Umbilical hernia in a 1-year-old female.
Umbilical hernias are generally asymptomatic protrusions of the abdominal wall. They are generally noted by parents or physicians shortly after birth. All families of patients with umbilical hernia should be counseled about signs of incarceration, which is rare in umbilical hernias and more common in smaller (≤1 cm) than larger defects. Incarceration presents with abdominal pain, bilious emesis, and a tender, hard mass protruding from the umbilicus. This constellation of symptoms mandates immediate exploration and repair of the hernia to avoid strangulation. More commonly, the child is asymptomatic and treatment is governed by the size of the defect, the age of the patient, and the concerns that the child and family have regarding the cosmetic appearance of the abdomen. When the defect is small and spontaneous closure is likely, most surgeons will delay surgical correction until 5 years of age. If closure does not occur by this time or a younger child has a very large or symptomatic hernia, it is reasonable to proceed to repair.
Repair of uncomplicated umbilical hernia is performed under general anesthesia as an outpatient procedure. A small curving incision that fits into the skin crease of the umbilicus is made, and the sac is dissected free from the overlying skin. The fascial defect is repaired with permanent or long-lasting absorbable, interrupted sutures that are placed in a transverse plane. The skin is closed using subcuticular sutures. The postoperative recovery is typically uneventful, and recurrence is rare, but more common in children with elevated intra-abdominal pressures such as those with a ventriculoperitoneal shunt.
Patent Urachus
During the development of the coelomic cavity, there is free communication between the urinary bladder and the abdominal wall through the urachus, which exits adjacent to the omphalomesenteric duct. Persistence of this tract results in a communication between the bladder and the umbilicus. The first sign of a patent urachus is moisture or urine flow from the umbilicus. Recurrent urinary tract infections can result. The urachus may be partially obliterated, with a remnant beneath the umbilicus in the extraperitoneal position as an isolated cyst that may be identified by US. A urachal cyst usually presents as an inflammatory mass inferior to the umbilicus. Initial treatment is drainage of the infected cyst followed by cyst excision as a separate procedure once the inflammation has resolved.
In the child with a persistently draining umbilicus, a diagnosis of patent urachus should be considered. The differential diagnosis includes an umbilical granuloma, which generally responds to local application of silver nitrate. The diagnosis of patent urachus is confirmed by umbilical exploration. The urachal tract is excised and the bladder is closed with an absorbable suture. A patent vitelline duct may also present with umbilical drainage. In this circumstance, there is a communication with the small intestine, often at the site of a Meckel's diverticulum. Treatment includes umbilical exploration with resection of the duct remnant (Fig. 39-29).
Patent vitelline duct. Note the communication between the umbilicus and the small bowel at the site of a Meckel's diverticulum.
Omphalocele
Omphalocele refers to a congenital defect of the abdominal wall in which the bowel and solid viscera are covered by peritoneum and amniotic membrane (Fig. 39-30). The umbilical cord inserts into the sac. Omphalocele can vary from a small defect with intestinal contents to giant omphalocele in which the abdominal wall defect measures 4 cm or more in diameter and contains liver. The overall incidence is approximately 1 in 5000 live births, with 1 in 10,000 that are giant omphaloceles. Omphalocele occurs in association with special syndromes such as exstrophy of the cloaca (vesicointestinal fissure), the Beckwith-Wiedemann constellation of anomalies (macroglossia, macrosomia, hypoglycemia, and visceromegaly and omphalocele), and Cantrell's pentalogy (lower thoracic wall malformations [cleft sternum], ectopia cordis, epigastric omphalocele, anterior midline diaphragmatic hernia, and cardiac anomalies). There is a 60% to 70% incidence of associated anomalies, especially cardiac (20%–40% of cases) and chromosomal abnormalities. Chromosomal anomalies are more common in children with smaller defects. Omphalocele is associated with prematurity (10%–50% of cases) and intrauterine growth restriction (20% of cases).
Giant omphalocele in a newborn male.
Immediate treatment of an infant with omphalocele consists of attending to the vital signs and maintaining the body temperature. A blood glucose should be evaluated because of the association with Beckwith-Wiedemann. The omphalocele should be covered to reduce fluid loss, but moist dressings may result in heat loss and are not indicated. No pressure should be placed on the omphalocele sac in an effort to reduce its contents, as this maneuver may increase the risk of rupture of the sac or may interfere with abdominal venous return. Prophylactic broad-spectrum antibiotics should be administered in case of rupture. The subsequent treatment and outcome are determined by the size of the omphalocele. In general terms, small to medium-sized defects have a significantly better prognosis than extremely large defects in which the liver is present. In these cases, not only is the management of the abdominal wall defect a significant challenge, but these patients often have concomitant pulmonary insufficiency that can lead to significant morbidity and mortality. If possible and if the pulmonary status will permit it, a primary repair of the omphalocele should be undertaken. This involves resection of the omphalocele membrane and closure of the fascia. A layer of prosthetic material may be required to achieve closure. In infants with a giant omphalocele, the defect cannot be closed primarily because there is not adequate intraperitoneal domain to reduce the viscera (see Fig. 39-30). Some infants may have associated congenital anomalies that complicate surgical repair, and because cardiac anomalies are common, an echocardiogram should be obtained prior to any procedure. If repair is contraindicated, a nonoperative approach can be used. The omphalocele sac can be treated with topical treatments. Various authors describe success with iodine-containing solutions, silver sulfadiazine, or saline, and some surgeons rotate these solutions because of the impact of iodine on the thyroid and the difficulty of cleaning off all of the silver sulfadiazine and its association with leukopenia. It typically takes 2 to 3 months before re-epithelialization occurs. In the past, mercury compounds were used, but they have been discontinued because of associated systemic toxicity. After epithelialization has occurred, attempts should be made to achieve closure of the anterior abdominal wall, but they may be delayed by associated pulmonary insufficiency. Such procedures typically require complex measures to achieve skin closure, including the use of biosynthetic materials or component separation. In cases of giant omphalocele, prolonged hospitalization is typical.
Gastroschisis
Gastroschisis represents a congenital anomaly characterized by a defect in the anterior abdominal wall through which the intestinal contents freely protrude. Unlike omphalocele, there is no overlying sac and the size of the defect is usually <4 cm. The abdominal wall defect is located at the junction of the umbilicus and normal skin and is almost always to the right of the umbilicus (Fig. 39-31). The umbilicus becomes partly detached, allowing free communication with the abdominal cavity. The appearance of the bowel provides some information with respect to the in utero timing of the defect. The intestine may be normal in appearance, suggesting that the rupture occurred relatively late during the pregnancy. More commonly, however, the intestine is thick, edematous, discolored, and covered with exudate, implying a more longstanding process. Progression to full enteral feeding is usually delayed, with diminished motility that may be related to these changes.
Gastroschisis in a newborn. Note the location of the umbilical cord and the edematous, thickened bowel.
Unlike infants born with omphalocele, associated anomalies are not usually seen with gastroschisis except for a 10% rate of intestinal atresia. This defect can readily be diagnosed on prenatal US (Fig. 39-32). There is no advantage to performing a cesarean section instead of a vaginal delivery. In a decade-long retrospective review, early delivery did not affect the thickness of bowel peel, yet patients delivered before 36 weeks had significantly longer length of stay in the hospital and time to enteral feeds. Based on these findings, fetal well-being should be the primary determinant of the timing of delivery for gastroschisis.
Prenatal ultrasound of a 30-week gestation fetus with a gastroschisis. Arrows point to the bowel outside within the amniotic fluid.
All infants born with gastroschisis require urgent surgical treatment. Of equal importance, these infants require vigorous fluid resuscitation in the range of 150 to 180 cc/kg/d to replace significant evaporative fluid losses. In many instances, the intestine can be returned to the abdominal cavity, and a primary surgical closure of the abdominal wall is performed. Some surgeons believe that they can facilitate primary closure with mechanical stretching of the abdominal wall, thorough orogastric suctioning with foregut decompression, rectal irrigation, and evacuation of meconium. Care must be taken to prevent markedly increased abdominal pressure during the reduction, which will lead to compression of the inferior vena cava, respiratory embarrassment, and abdominal compartment syndrome. To avoid this complication, it is helpful to monitor the bladder or airway pressures during reduction. In infants whose intestine has become thickened and edematous, it may be impossible to reduce the bowel into the peritoneal cavity in the immediate postnatal period. Under such circumstances, a plastic spring-loaded silo can be placed onto the bowel and secured beneath the fascia or a sutured silastic silo constructed. The silo covers the bowel and allows for graduated reduction on a daily basis as the edema in the bowel wall decreases (Fig. 39-33). It is important to ensure that the silo-fascia junction does not become a constricting point or "funnel" in which case the intestine will be injured upon return to the peritoneum. In this case, the fascial opening must be enlarged. Surgical closure can usually be accomplished within approximately 1 to 2 weeks. A prosthetic piece of material may be required to bring the edges of the fascia together. If an atresia is noted at the time of closure, it is prudent to reduce the bowel at the first operation, then to return after several weeks once the edema has resolved to correct the atresia. Intestinal function does not typically return for several weeks in patients with gastroschisis. This is especially true if the bowel is thickened and edematous. As a result, these patients will require central line placement and institution of TPN in order to grow. Feeding advancement should be slow and typically requires weeks to arrive at full enteral nutrition.
Use of a silo in a patient with gastroschisis to allow the bowel wall edema to resolve to facilitate subsequent closure of the abdominal wall.
Prune-Belly Syndrome
Prune-belly syndrome refers to a disorder that is characterized by extremely lax lower abdominal musculature, dilated urinary tract including the bladder, and bilateral undescended testes (Fig. 39-34). The term prune-belly syndrome appropriately describes the wrinkled appearance of the anterior abdominal wall that characterizes these patients. Prune-belly syndrome is also known as Eagle-Barrett syndrome and the triad syndrome, because of the three major manifestations. The incidence is significantly higher in males. Patients manifest a variety of comorbidities. The most significant is pulmonary hypoplasia, which is not survivable in the most severe cases. Skeletal abnormalities include dislocation or dysplasia of the hip and pectus excavatum.
Eagle-Barrett (prune-belly) syndrome. Notice the lax, flaccid abdomen.
The major genitourinary manifestation in prune-belly syndrome is ureteral dilation. The ureters are typically long and tortuous and become more dilated distally. Ureteric obstruction is rarely present, and the dilation may be caused by decreased smooth muscle and increased collagen in the ureters. Approximately 80% of these patients will have some degree of vesicoureteral reflux, which can predispose to urinary tract infection. Despite the marked dilatation of the urinary tract, most children with prune-belly syndrome have adequate renal parenchyma for growth and development. Factors associated with the development of long-term renal failure include the presence of abnormal kidneys on US or renal scan and persistent pyelonephritis.
Despite the ureteric dilation, there is currently no role for ureteric surgery unless an area of obstruction develops. The testes are invariably intra-abdominal, and bilateral orchiopexy can be performed in conjunction with abdominal wall reconstruction at 6 to 12 months of age. Despite orchiopexy, fertility in a boy with prune-belly syndrome is unlikely as spermatogenesis over time is insufficient. Deficiencies in the production of prostatic fluid and a predisposition to retrograde ejaculation contribute to infertility. Abdominal wall repair is accomplished through an abdominoplasty, which typically requires a transverse incision in the lower abdomen extending into the flanks.
An understanding of the management of pediatric inguinal hernias is a central component of modern pediatric surgical practice. Inguinal hernia repair represents one of the most common operations performed in children. The presence of an inguinal hernia in a child is an indication for surgical repair. The operation is termed a herniorrhaphy because it involves closing off the patent processus vaginalis. This is to be contrasted with the hernioplasty that is performed in adults, which requires a reconstruction of the inguinal floor.
In order to understand how to diagnose and treat inguinal hernias in children, it is critical to understand their embryologic origin. It is very useful to describe these events to the parents, who often are under the misconception that the hernia was somehow caused by their inability to console their crying child or by the child's high activity level. Inguinal hernia results from a failure of closure of the processus vaginalis, a finger-like projection of the peritoneum that accompanies the testicle as it descends into the scrotum. Closure of the processus vaginalis normally occurs a few months prior to birth. This explains the high incidence of inguinal hernias in premature infants. When the processus vaginalis remains completely patent, a communication persists between the peritoneal cavity and the groin, resulting in a hernia. Partial closure can result in entrapped fluid, which is known as a hydrocele. A communicating hydrocele refers to a hydrocele that is in communication with the peritoneal cavity and can therefore be thought of as a hernia. Using the classification system that is typically applied to adult hernias, all congenital hernias in children are by definition indirect inguinal hernias. Children also present with direct inguinal and femoral hernias, although these are much less common.
Clinical Manifestation
Inguinal hernias occur more commonly in males than females (10:1) and are more common on the right side than the left. Infants are at high risk for incarceration of an inguinal hernia because of the narrow inguinal ring. Patients most commonly present with a groin bulge that is noticed by the parents as they change the diaper (Fig. 39-35). Older children may notice the bulge themselves. On examination, the cord on the affected side will be thicker, and pressure on the lower abdomen usually will display the hernia on the affected side. The presence of an incarcerated hernia is manifested by a firm bulge that does not spontaneously resolve and may be associated with fussiness and irritability in the child. The infant who has a strangulated inguinal hernia will manifest an edematous, tender bulge in the groin, occasionally with overlying skin changes. The child will eventually develop intestinal obstruction, peritonitis, and systemic toxicity.
Right inguinal hernia in a 4-month-old male. The arrows point to the bulge in the right groin.
Usually an incarcerated hernia can be reduced. Occasionally this may require light sedation. Gentle pressure is applied on the sac from below in the direction of the internal inguinal ring. Following reduction of the incarcerated hernia, the child may be admitted for observation, and herniorrhaphy is performed within the next 24 hours to prevent recurrent incarceration. Alternatively, the child may be scheduled for surgery at the next available time slot. If the hernia cannot be reduced or if evidence of strangulation is present, emergency operation is necessary. This may require a laparotomy and bowel resection.
When the diagnosis of inguinal hernia is made in an otherwise normal child, operative repair should be planned. Spontaneous resolution does not occur, and therefore, a nonoperative approach cannot ever be justified. An inguinal hernia in a female infant or child frequently contains an ovary rather than intestine. Although the gonad usually can be reduced into the abdomen by gentle pressure, it often prolapses in and out until surgical repair is carried out. In some patients, the ovary and fallopian tube constitute one wall of the hernia sac (sliding hernia), and in these patients, the ovary can be reduced effectively only at the time of operation. If the ovary is irreducible, prompt hernia repair is indicated to prevent ovarian torsion or strangulation.
When a hydrocele is diagnosed in infancy and there is no evidence of a hernia, observation is proper therapy until the child is older than 12 months. If the hydrocele has not disappeared by 12 months, invariably there is a patent processus vaginalis, and operative hydrocelectomy with excision of the processus vaginalis is indicated. When the first signs of a hydrocele are seen after 12 months of age, the patient should undergo elective hydrocelectomy, which in a child is always performed through a groin incision. Aspiration of hydroceles is discouraged, since almost all without a patent processus vaginalis will resorb spontaneously, and those with a communication to the peritoneum will recur and require operative repair eventually. Transillumination as a method to distinguish between hydrocele and hernia is nonspecific. A noncommunicating hydrocele is better identified by palpation of a nonreducible oval structure that appears to have a blunt end below the external ring, indicating an isolated fluid collection without a patent connection to the peritoneum.
Surgical Repair
The repair of a pediatric inguinal hernia can be extremely challenging, particularly in the premature child with incarceration. A small incision is made in a skin crease in the groin directly over the internal inguinal ring. Scarpa's fascia is seen and divided. The external oblique muscle is dissected free from overlying tissue, and the location of the external ring is confirmed. The external oblique aponeurosis is then opened along the direction of the external oblique fibers over the inguinal canal. The undersurface of the external oblique is then cleared from surrounding tissue. The cremasteric fibers are separated from the cord structures and hernia sac, and these are then elevated into the wound. Care is taken not to grasp the vas deferens. The hernia sac is then dissected up to the internal ring and doubly suture ligated. The distal part of the hernia sac is opened widely to drain any hydrocele fluid. When the hernia is very large and the patient very small, tightening of the internal inguinal ring or even formal repair of the inguinal floor may be necessary, although the vast majority of children do not require any treatment beyond high ligation of the hernia sac.
Controversy exists regarding the role for exploration of an asymptomatic opposite side in a child with an inguinal hernia. Several reports indicate that frequency of a patent processus vaginalis on the side opposite the obvious hernia is approximately 30%, although this figure decreases with increasing age of the child. Management options include never exploring the opposite side or exploring only under certain conditions such as in premature infants or in patients in whom incarceration is present. The opposite side may readily be explored laparoscopically. To do so, a blunt 3-mm trocar is placed into the hernia sac of the affected side. The abdominal cavity is insufflated, and the 2.7-mm 70° camera is placed through the trocar such that the opposite side is visualized. The status of the processes vaginalis on the opposite side can be visualized. However, the presence of a patent processus vaginalis by laparoscopy does not always imply the presence of a hernia.
Several authors have now reported a completely laparoscopic approach in the management of inguinal hernias in children. This technique requires insufflation through the umbilicus and the placement of an extraperitoneal suture to ligate the hernia sac. Proponents of this procedure emphasize the fact that no groin incision is used and there is a decreased chance of injuring cord structures. The long-term results of this technique remain to be established.
Inguinal hernias in children recur in less than 1% of patients, and recurrences usually result from missed hernia sacs at the first procedure, a direct hernia, or a missed femoral hernia. All children should have local anesthetic administered either by caudal injection or by direct injection into the wound. Spinal anesthesia in the preterm infant decreases the risk of postoperative apnea when compared with general anesthesia.
Undescended Testis
The term undescended testicle (cryptorchidism) refers to the interruption of the normal descent of the testis into the scrotum. The testicle may reside in the retroperineum, in the internal inguinal ring, in the inguinal canal, or even at the external ring. The testicle begins as a thickening on the urogenital ridge in the fifth to sixth week of embryologic life. In the seventh and eighth months, the testicle descends along the inguinal canal into the upper scrotum, and with its progress, the processus vaginalis is formed and pulled along with the migrating testicle. At birth, approximately 95% of infants have the testicle normally positioned in the scrotum.
A distinction should be made between an undescended testicle and an ectopic testicle. An ectopic testis, by definition, is one that has passed through the external ring in the normal pathway and then has come to rest in an abnormal location overlying either the rectus abdominis or external oblique muscle, or the soft tissue of the medial thigh, or behind the scrotum in the perineum. A congenitally absent testicle results from failure of normal development or an intrauterine accident leading to loss of blood supply to the developing testicle.
The incidence of undescended testes is approximately 30% in preterm infants and 1% to 3% in term infants. For diagnosis, the child should be examined in the supine position, where visual inspection may reveal a hypoplastic or poorly rugated scrotum. Usually a unilateral undescended testicle can be palpated in the inguinal canal or in the upper scrotum. Occasionally, the testicle will be difficult or impossible to palpate, indicating either an abdominal testicle or congenital absence of the gonad. If the testicle is not palpable in the supine position, the child should be examined with his legs crossed while seated. This maneuver diminishes the cremasteric reflex and facilitates identification of the location of the testicle. If there is uncertainty regarding location of a testis, repeated evaluations over time may be helpful.
It is now established that cryptorchid testes demonstrate an increased predisposition to malignant degeneration. In addition, fertility is decreased when the testicle is not in the scrotum. For these reasons, surgical placement of the testicle in the scrotum (orchidopexy) is indicated. It should be emphasized that this procedure does improve the fertility potential, although it is never normal. Similarly, the testicle is still at risk of malignant change, although its location in the scrotum facilitates potentially earlier detection of a testicular malignancy. Other reasons to consider orchidopexy include the risk of trauma to the testicle located at the pubic tubercle and increased incidence of torsion, as well as the psychological impact of an empty scrotum in a developing male. The reason for malignant degeneration is not established, but the evidence points to an inherent abnormality of the testicle that predisposes it to incomplete descent and malignancy rather than malignancy as a result of an abnormal environment.
Males with bilateral undescended testicles are often infertile. When the testicle is not within the scrotum, it is subjected to a higher temperature, resulting in decreased spermatogenesis. Mengel and coworkers studied 515 undescended testicles by histology and demonstrated a decreasing presence of spermatogonia after 2 years of age. Despite orchidopexy, the incidence of infertility is approximately two times higher in men with unilateral orchidopexy compared to men with normal testicular descent. Consequently, it is now recommended that the undescended testicle be surgically repositioned by 1 year of age.
The use of chorionic gonadotropin occasionally may be effective in patients with bilateral undescended testes, suggesting that these patients are more apt to have a hormone insufficiency than children with unilateral undescended testicle. The combination of micro-penis and bilateral undescended testes is an indication for hormonal evaluation and testosterone replacement if indicated. If there is no testicular descent after a month of endocrine therapy, operative correction should be undertaken. A child with unilateral cryptorchidism should have surgical correction of the problem. The operation is typically performed through a combined groin and scrotal incision. The cord vessels are fully mobilized, and the testicle is placed in a dartos pouch within the scrotum. An inguinal hernia often accompanies a cryptorchid testis. This should be repaired at the time of orchidopexy.
Patients with a nonpalpable testicle present a challenge in management. The current approach involves laparoscopy to identify the location of the testicle. If the spermatic cord is found to traverse the internal ring or the testis is found at the ring and can be delivered into the scrotum, a groin incision is made and an orchidopexy is performed. If an abdominal testis is identified that is too far to reach the scrotum, a two-stage Fowler-Stephens approach is used. In the first stage, the testicular vessels can be clipped via laparotomy or laparoscopically. This promotes neovasculogenesis along the vas deferens. Several months later, the second stage is performed during which the testis is mobilized intra-abdominally along with a swath of peritoneum with collateralized blood supply along the vas. This may be done laparoscopically as well. Preservation of the gubernacular attachments with its collaterals to the testicle may confer improved testicular survival following orchidopexy in over 90% of cases. It is, nonetheless, preferable to preserve the testicular vessels whenever possible and complete mobilization of the testicle with its vessels intact. Some surgeons advocate aggressive mobilization of testicular vessels up to the renal hilum if the intra-abdominal testis is within 1 or 2 cm of the internal ring. Other surgeons feel that the staged approach to orchidopexy is superior. To date, no large-scale trial has been performed to answer this question. In either case, meticulous mobilization of the intra-abdominal testis is critical for its survival and successful pexy.
Vaginal Anomalies
Surgical diseases of the vagina in children are either congenital or acquired. Congenital anomalies include a spectrum of diseases that range from simple defects (imperforate hymen) to more complex forms of vaginal atresia, including distal, proximal, and, most severe, complete. These defects are produced by abnormal development of müllerian ducts and/or urogenital sinus. The diagnosis is made most often by physical examination. Secretions into the obstructed vagina produce hydrocolpos, which may present as a large, painful abdominal mass. The anatomy may be defined using US. Pelvic MRI provides the most thorough and accurate assessment of the pelvic structures. Treatment is dependent on the extent of the defect. For an imperforate hymen, division of the hymen is curative. More complex forms of vaginal atresia require mobilization of the vaginal remnants and creation of an anastomosis at the perineum. Laparoscopy can be extremely useful in mobilizing the vagina, in draining hydrocolpos, and in evaluating the internal genitalia. Complete vaginal atresia requires the construction of skin flaps or the creation of a neovagina using a segment of colon.
The most common acquired disorder of the vagina is the straddle injury. This often occurs as young girls fall on blunt objects, which cause a direct injury to the perineum. Typical manifestations include vaginal bleeding and inability to void. Unless the injury is extremely superficial, patients should be examined in the operating room where the lighting is optimal and sedation can be administered. Vaginal lacerations are repaired using absorbable sutures, and the proximity to the urethra should be carefully assessed. Prior to hospital discharge, it is important that girls are able to void spontaneously. In all cases of vaginal trauma, it is essential that the patient be assessed for the presence of sexual abuse. In these cases, early contact with the sexual abuse service is necessary, so that the appropriate microbiologic and photographic evidence can be obtained.
Ovarian Cysts and Tumors
Pathologic Classification
Ovarian cysts and tumors may be classified as nonneoplastic or neoplastic. Nonneoplastic lesions include cysts (simple, follicular, inclusion, paraovarian, or corpus luteum), endometriosis, and inflammatory lesions. Neoplastic lesions are classified based on the three primordia that contribute to the ovary: mesenchymal components of the urogenital ridge, germinal epithelium overlying the urogenital ridge, and germ cells migrating from the yolk sac. The most common variety is germ cell tumors. Germ cell tumors are classified based on the degree of differentiation and the cellular components involved. The least differentiated tumors are the dysgerminomas, which share features similar to the seminoma in males. Although these are malignant tumors, they are extremely sensitive to radiation and chemotherapy. The most common lesions are the teratomas, which may be mature, immature, or malignant. The degree of differentiation of the neural elements of the tumor determines the degree of immaturity. The sex cord stromal tumors arise from the mesenchymal components of the urogenital ridge. These include the granulosa-theca cell tumors and the Sertoli-Leydig cell tumors. These tumors often produce hormones that result in precocious puberty or hirsutism, respectively. Although rare, epithelial tumors do occur in children. These include serous and mucinous cystadenomas.
Children with ovarian lesions usually present with abdominal pain. Other signs and symptoms include a palpable abdominal mass, evidence of urinary obstruction, symptoms of bowel obstruction, and endocrine imbalance. The surgical approach depends on the appearance of the mass at operation (i.e., whether it is benign-appearing or is suspicious for malignancy). In the case of a simple ovarian cyst, surgery depends on the size of the cyst and the degree of symptoms it causes. In general, large cysts (over 4–5 cm in size) should be resected, as they are unlikely to resolve, may be at risk of torsion, and may mask an underlying malignancy. Resection may be performed laparoscopically; ovarian tissue should be spared in all cases.
For ovarian lesions that appear malignant, it is important to obtain tumor markers including α-fetoprotein (teratomas), lactate dehydrogenase (dysgerminoma), β-human chorionic gonadotropin (choriocarcinoma), and CA-125 (epithelial tumors). Although the diagnostic sensitivity of these markers is not always reliable, they provide material for postoperative follow-up and indicate the response to therapy. When a malignancy is suspected, the patient should undergo a formal cancer operation. This procedure is performed through either a midline incision or a Pfannenstiel approach. Ascites and peritoneal washings should be collected for cytologic study. The liver and diaphragm are inspected carefully for metastatic disease. An omentectomy is performed if there is any evidence of tumor present. Pelvic and para-aortic lymph nodes are biopsied, and the primary tumor is resected completely. Finally, the contralateral ovary is carefully inspected, and if a lesion is seen, it should be biopsied. Dysgerminomas and epithelial tumors may be bilateral in up to 15% of cases. It is occasionally possible to preserve the ipsilateral fallopian tube. More radical procedures are not indicated.
Ovarian Cysts in the Newborn
An increasing number of ovarian cysts are being detected by prenatal US. In the past, surgical excision was recommended for all cysts greater than 5 cm in diameter because of the perceived risk of ovarian torsion. More recently, it has become apparent from serial US examinations that many of these lesions will resolve spontaneously. Therefore, asymptomatic, simple cysts may be observed, and surgery can be performed only when they fail to decrease in size or become symptomatic. Typically, resolution occurs by approximately 6 months of age. A laparoscopic approach is preferable in these cases. By contrast, complex cysts of any size require surgical intervention at presentation.
Ambiguous Genitalia
Normal sexual differentiation occurs in the sixth fetal week. In every fetus, wolffian (male) and müllerian (female) ducts are present until the onset of sexual differentiation. Normal sexual differentiation is directed by the sex-determining region of the Y chromosome (SRY). This is located on the distal end of the short arm of the Y chromosome. SRY provides a genetic switch that initiates gonadal differentiation in the mammalian urogenital ridge. Secretion of müllerian-inhibiting substance (MIS) by the Sertoli cells of the seminiferous tubules results in regression of the müllerian duct, the anlage of the uterus, fallopian tubes, and the upper vagina. Therefore, the result of MIS secretion is a phenotypic male. In the absence of SRY in the Y chromosome, MIS is not produced, and the müllerian duct derivatives are preserved. Thus, the female phenotype prevails.
In order for the male phenotype to develop, the embryo must have a Y chromosome, the SRY must be normal without point mutations or deletions, testosterone and MIS must be produced by the differentiated gonad, and the tissues must respond to these hormones. Any disruption of the orderly steps in sexual differentiation may result in disorders of sex development (DSDs), formerly known as intersex syndromes. DSDs are now classified as: (a) ovotesticular DSD or 46,XX testicular DSD (formerly referred to as true hermaphrodite), (b) 46,XY DSD (male pseudohermaphrodite), (c) 46,XX DSD (female pseudohermaphrodite), and (d) mixed gonadal dysgenesis (usually underdeveloped or imperfectly formed gonads).
Ovotesticular DSD or 46,XX Testicular DSD
This represents the rarest form of ambiguous genitalia. Patients have both normal male and female gonads, with an ovary on one side and a testis on the other. Occasionally, an ovotestis is present on one or both sides. The majority of these patients have a 46,XX karyotype. Both the testis and the testicular portion of the ovotestis should be removed.
46,XY DSD
This condition occurs in infants with an XY karyotype but deficient masculinization of the external genitalia. Bilateral testes are present, but the duct structures differentiate partly as phenotypic females. Causes include inadequate testosterone production due to biosynthetic error, inability to convert testosterone to dihydrotestosterone due to 5-α-reductase deficiency, or deficiencies in androgen receptors. The latter disorder is termed testicular feminization syndrome. Occasionally, the diagnosis in these children is made during routine inguinal herniorrhaphy in a phenotypic female at which time testes are found. The testes should be resected due to the risk of malignant degeneration, although this should be performed only after a full discussion with the family has occurred.
46,XX DSD
The most common cause of this disorder is congenital adrenal hyperplasia. These children have a 46,XX karyotype but have been exposed to excessive androgens in utero. Common enzyme deficiencies include 21-hydroxylase, 11-hydroxylase, and 3-β-hydroxysteroid dehydrogenase. These deficiencies result in overproduction of intermediary steroid hormones, which results in masculinization of the external genitalia of the XX fetus. These patients are unable to synthesize cortisol. In 90% of cases, deficiency of 21-hydroxylase causes adrenocorticotropic hormone (ACTH) to stimulate the secretion of excessive quantities of adrenal androgen, which masculinizes the developing female (Fig. 39-36). These infants are prone to salt loss and require cortisol replacement. Those with mineralocorticoid deficiency also require fludrocortisone replacement.
Ambiguous genitalia manifest as enlarged clitoris and labioscrotal folds in a baby with the adrenogenital syndrome.
Mixed Gonadal Dysgenesis
This syndrome is associated with dysgenetic gonads and retained müllerian structures. The typical karyotype is mosaic, usually 45,XO/46,XY. There is a high incidence of malignant tumors in the dysgenetic gonads, most commonly gonadoblastoma. Therefore, they should be removed.
In the differential diagnosis of patients with intersex anomalies, the following diagnostic steps are necessary: (a) evaluation of the genetic background and family history; (b) assessment of the anatomic structures by physical examination, US, and/or chromosome studies; (c) determination of biochemical factors in serum and urine to evaluate the presence of an enzyme defect; and (d) laparoscopy for gonadal biopsy. Treatment should include correction of electrolyte and volume losses in cases of congenital adrenal hyperplasia and replacement of hormone deficiency. Surgical assignment of gender should never be determined at the first operation. Although historically female gender had been assigned, there is abundant and convincing evidence that raising a genotypic male as a female has devastating consequences, not only anatomically but also psychosocially. This is particularly relevant given the role of pre- and postnatal hormones on gender imprinting and identity. In general terms, surgical reconstruction should be performed after a full genetic workup and with the involvement of pediatric endocrinologists, pediatric plastic surgeons, and ethicists with expertise in gender issues. Discussion with the family also plays an important role. This approach will serve to reduce the anxiety associated with these disorders and will help to ensure the normal physical and emotional development of these patients.
Cancer is the second leading cause of death in children after trauma and accounts for approximately 11% of all pediatric deaths in the United States. Several features distinguish pediatric from adult cancers, including the presence of tumors that are predominantly seen in children, such as neuroblastoma and germ cell tumors, and the favorable response to chemotherapy observed for many pediatric solid malignancies, even in the presence of metastases.
Wilms' Tumor
Wilms' tumor is the most common primary malignant tumor of the kidney in children. There are approximately 500 new cases annually in the United States, and most are diagnosed between 1 and 5 years with the peak incidence at age 3. Advances in the care of patients with Wilms' tumor have resulted in an overall cure rate of roughly 90%, even in the presence of metastatic spread. The tumor usually develops in otherwise healthy children as an asymptomatic mass in the flank or upper abdomen. Frequently, the mass is discovered by a parent while bathing or dressing the child. Other symptoms include hypertension, hematuria, obstipation, and weight loss. Occasionally the mass is discovered following blunt abdominal trauma.
Genetics of Wilms' Tumor
Wilms' tumor can arise from both germline and somatic mutations and can occur in the presence or absence of a family history. Nearly 97% of Wilms' tumors are sporadic, in that they occur in the absence of a heritable or congenital cause or risk factor. When a heritable risk factor is identified, the affected children often present at an earlier age and are frequently bilateral. Most of these tumors are associated with germline mutations. It is well established that there is a genetic predisposition to Wilms' tumor in the WAGR syndrome, which consists of Wilms' tumor, aniridia, genitourinary abnormalities, and mental retardation. In addition, there is an increased incidence of Wilms' tumor in certain overgrowth conditions, particularly Beckwith-Wiedemann syndrome and hemihypertrophy. The WAGR syndrome has been shown to result from the deletion of one copy each of the Wilms' tumor gene, WT1, and the adjacent aniridia gene, PAX6, on chromosome 11p13. Beckwith-Wiedemann syndrome is an overgrowth syndrome that is characterized by visceromegaly, macroglossia, and hyperinsulinemic hypoglycemia. It arises from mutations at the 11p15.5 locus. There is evidence to suggest that analysis of the methylation status of several genes in the 11p15 locus could predict the individual risk of developing Wilms' tumor. Importantly, most patients with Wilms' tumor do not have mutations at these genetic loci.
Before operation, all patients suspected of having Wilms' tumor should undergo abdominal and chest CT. These studies characterize the mass, identify the presence of metastases, and provide information on the opposite kidney (Fig. 39-37). CT scanning also indicates the presence of nephrogenic rests, which are precursor lesions to Wilms' tumor. An abdominal US should be performed to evaluate the presence of renal vein or vena caval extension.
Wilms' tumor of the right kidney (arrow) in a 3-year-old girl.
The management of patients with Wilms' tumor has been carefully analyzed within the context of large studies involving thousands of patients. These studies have been coordinated by the National Wilms' Tumor Study Group (NWTSG) in North America and the International Society of Paediatric Oncology (SIOP), mainly involving European countries. Significant differences in the approach to patients with Wilms' tumor have been highlighted by these studies. NWTSG supports a strategy of surgery followed by chemotherapy in most instances, whereas the SIOP approach is to shrink the tumor using preoperative chemotherapy. There are instances were preoperative chemotherapy is supported by both groups, including the presence of bilateral involvement or inferior vena cava involvement that extends above the hepatic veins and involvement of a solitary kidney by Wilms' tumor. The NWTSG proponents argue that preoperative therapy in other instances results in a loss of important staging information, and therefore places patients at higher risk for recurrence; alternatively, it may lead to overly aggressive treatment in some cases and greater morbidity. However, the overall survival rates are not different between the NWTSG and SIOP approaches.
The goal of surgery is complete removal of the tumor. It is crucial to avoid tumor rupture or injury to contiguous organs. A sampling of regional lymph nodes should be included, and all suspicious nodes should be sampled. Typically a transverse abdominal incision is made, and a transperitoneal approach is used. The opposite side is carefully inspected to ensure that there is no disease present. Although historically this involved the complete mobilization of the contralateral kidney, current evidence indicates that preoperative high-resolution CT scanning is of sufficient accuracy for the detection of clinically significant lesions if they are present. Provided only unilateral disease is present, a radical nephroureterectomy is then performed with control of the renal pedicle as an initial step. If there is spread above the hepatic veins, an intrathoracic approach may be required. If bilateral disease is encountered, both lesions are biopsied, and chemotherapy is administered followed by a nephron-sparing procedure.
Following nephroureterectomy for Wilms' tumor, the need for chemotherapy and/or radiation therapy is determined by the histology of the tumor and the clinical stage of the patient (Table 39-3). Essentially, patients who have disease confined to one kidney that is completely excised surgically receive a short course of chemotherapy and can expect a 97% 4-year survival, with tumor relapse rare after that time. Patients with more advanced disease or with unfavorable histology receive more intensive chemotherapy and radiation. Even in stage IV, cure rates of 80% are achieved. The survival rates are worse in the small percentage of patients considered to have unfavorable histology.
Table 39-3Staging of Wilms' tumor
Table 39-3 Staging of Wilms' tumor
Stage I: Tumor limited to the kidney and completely excised.
Stage II: Tumor that extends beyond the kidney but is completely excised. No residual tumor is apparent at or beyond the margins of excision. The tumor was biopsied, or there was local spillage of tumor confined to the flank.
Stage III: Residual tumor confined to the abdomen. Lymph nodes in the renal hilus, the periaortic chains, or beyond contain tumor. Diffuse peritoneal contamination by the tumor, such as by spillage of tumor beyond the flank before or during surgery or by tumor growth that has penetrated through the peritoneal surface. Implants are found on the peritoneal surfaces. Tumor extends beyond the surgical margins either microscopically or grossly. Tumor is not completely resectable because of local infiltration into vital structures.
Stage IV: Hematogenous metastases
Stage V: Bilateral renal involvement
Source: D'Angio GJ, Breslow N, Beckwith JB, et al. Treatment of Wilms' tumor. Results of the Third National Wilms' Tumor Study. Cancer. 1989;64:349-360.
Neuroblastoma is the third most common pediatric malignancy and accounts for approximately 10% of all childhood cancers. The vast majority of patients have advanced disease at the time of presentation, and unlike Wilms' tumor, in which cure is expected in the vast majority of patients, the overall survival of patients with neuroblastoma is significantly lower. Over 80% of cases present before the age of 4 years, and the peak incidence is 2 years of age. Neuroblastomas arise from the neural crest cells and show different levels of differentiation. The tumor originates most frequently in the adrenal glands, posterior mediastinum, neck, or pelvis but can arise in any sympathetic ganglion. The clinical presentation depends on the site of the primary and the presence of metastases.
Two thirds of these tumors are first noted as an asymptomatic abdominal mass. The tumor may cross the midline, and a majority of patients will already show signs of metastatic disease. Occasionally, children may experience pain from the tumor mass or from bony metastases. Proptosis and periorbital ecchymosis may occur due to the presence of retrobulbar metastasis. Because they originate in paraspinal ganglia, neuroblastomas may invade through neural foramina and compress the spinal cord, causing muscle weakness or sensory changes. Rarely, children may have severe watery diarrhea due to the secretion of vasoactive intestinal peptide by the tumor or have paraneoplastic neurologic findings including cerebellar ataxia or opsoclonus/myoclonus.
Diagnostic Evaluation
Since these tumors derive from the sympathetic nervous system, catecholamines and their metabolites will be produced at increased levels. These include elevated levels of serum catecholamines (dopamine, norepinephrine) or urine catecholamine metabolites (vanillylmandelic acid [VMA] or homovanillic acid [HVA]). Measurement of VMA and HVA in serum and urine aids in the diagnosis and in monitoring adequacy of future treatment and recurrence. The minimum criterion for a diagnosis of neuroblastoma is based on one of the following: (a) an unequivocal pathologic diagnosis made from tumor tissue by light microscopy (with or without immunohistology, electron microscopy, or increased levels of serum catecholamines or urinary catecholamine metabolites); or (b) the combination of bone marrow aspirate or biopsy containing unequivocal tumor cells and increased levels of serum catecholamines or urinary catecholamine metabolites as described earlier.
The patient should be evaluated by abdominal CT, which may show displacement and occasionally obstruction of the ureter of an intact kidney (Fig. 39-38). Prior to the institution of therapy, a complete staging workup should be performed. This includes radiograph of the chest, bone marrow biopsy, and radionuclide scans to search for metastases. Any abnormality on chest x-ray should be followed up with CT of the chest.
Abdominal neuroblastoma arising from the right retroperitoneum (arrow).
Prognostic Indicators
A number of biologic variables have been studied in children with neuroblastoma. An open biopsy is required in order to provide tissue for this analysis. Hyperdiploid tumor DNA is associated with a favorable prognosis, and N-myc amplification is associated with a poor prognosis regardless of patient age. The Shimada classification describes tumors as either favorable or unfavorable histology based on the degree of differentiation, the mitosis-karyorrhexis index, and the presence or absence of schwannian stroma. In general, children of any age with localized neuroblastoma and infants younger than 1 year of age with advanced disease and favorable disease characteristics have a high likelihood of disease-free survival. By contrast, older children with advanced-stage disease have a significantly decreased chance for cure despite intensive therapy. For example, aggressive multiagent chemotherapy has resulted in a 2-year survival rate of approximately 20% in older children with stage IV disease. Neuroblastoma in the adolescent has a worse long-term prognosis regardless of stage or site and, in many cases, a more prolonged course.
The goal of surgery is complete resection. However, this is often not possible at initial presentation due to the extensive locoregional spread of the tumor at the time of presentation. Under these circumstances, a biopsy is performed and preoperative chemotherapy is provided based on the stage of the tumor. After neoadjuvant treatment has been administered, surgical resection is performed. The principal goal of surgery is to obtain at least 95% resection, without compromising major structures. Abdominal tumors are approached through a transverse incision. Thoracic tumors may be approached through a posterolateral thoracotomy or through a thoracoscopic approach. These may have an intraspinal component. In all cases of intrathoracic neuroblastoma, particularly those at the thoracic inlet, it is important to be aware of the possibility of a Horner's syndrome (anhidrosis, ptosis, meiosis) developing. This typically resolves, although it may take many months to do so.
Neuroblastoma in Infants
Spontaneous regression of neuroblastoma has been well described in infants, especially in those with stage IVS disease. Regression generally occurs only in tumors with a near triploid number of chromosomes that also lack N-myc amplification and loss of chromosome 1p. Recent studies indicate that infants with asymptomatic, small, low-stage neuroblastoma detected by screening may have tumors that spontaneously regress. These patients may be observed safely without surgical intervention or tissue diagnosis.
Rhabdomyosarcoma is a primitive soft tissue tumor that arises from mesenchymal tissues. The most common sites of origin include the head and neck (36%), extremities (19%), genitourinary tract (21%), and trunk (9%), although the tumor can arise virtually anywhere. The clinical presentation of the tumor depends on the site of origin. The diagnosis is confirmed with incisional or excisional biopsy after evaluation by MRI, CT scans of the affected area and the chest, and bone marrow biopsy. The tumor grows locally into surrounding structures and metastasizes widely to lung, regional lymph nodes, liver, brain, and bone marrow. The staging system for rhabdomyosarcoma is based on the TNM system, as established by the Soft Tissue Sarcoma Committee of the Children's Oncology Group. It is shown in Table 39-4. Surgery is an important component of the staging strategy and involves biopsy of the lesion and evaluation of lymphatics. Primary resection should be undertaken when complete excision can be performed without causing disability. If this is not possible, the lesion is biopsied, and intensive chemotherapy is administered. It is important to plan the biopsy so that it does not interfere with subsequent resection. After the tumor has decreased in size, resection of gross residual disease should be performed. Radiation therapy is effective in achieving local control when microscopic or gross residual disease exists following initial treatment. Patients with completely resected tumors of embryonal histology do well without radiation therapy, but radiation therapy benefits patients with group I tumors with alveolar or undifferentiated histology.
Table 39-4Staging of rhabdomyosarcoma
Table 39-4 Staging of rhabdomyosarcoma
Stage 1: Localized disease involving the orbit or head and neck (excluding parameningeal sites), genitourinary region (excluding bladder/prostate sites), or biliary tract (favorable sites).
Stage 2: Localized disease of any other primary site not included in the stage 1 category (unfavorable sites). Primary tumors must be ≤5 cm in diameter, and there must be no clinical regional lymph node involvement by tumor.
Stage 3: Localized disease of any other primary site. These patients differ from stage 2 patients by having primary tumors greater than 5 cm and/or regional node involvement.
Stage 4: Metastatic disease at diagnosis.
Sources: Lawrence W Jr, Gehan EA, Hays DM, et al. Prognostic significance of staging factors of the UICC staging system in childhood rhabdomyosarcoma: a report from the Intergroup Rhabdomyosarcoma Study (IRS-II). J Clin Oncol. 1987;5:46-54.
Lawrence W Jr, Anderson JR, Gehan EA, et al. Pretreatment TNM staging of childhood rhabdomyosarcoma: a report of the Intergroup Rhabdomyosarcoma Study Group. Children's Cancer Study Group. Pediatric Oncology Group. Cancer. 1997;80:1165-1170.
The prognosis for rhabdomyosarcoma is related to the site of origin, resectability, presence of metastases, number of metastatic sites, and histopathology. Primary sites with more favorable prognoses include the orbit and nonparameningeal head and neck, paratestis and vagina (nonbladder, nonprostate genitourinary), and biliary tract. Patients with tumors less than 5 cm in size have improved survival compared to children with larger tumors, whereas children with metastatic disease at diagnosis have the poorest prognosis. Tumor histology influences prognosis. The embryonal variant is favorable, whereas the alveolar subtype has an unfavorable prognosis.
Teratoma
Teratomas are tumors composed of tissue from all three embryonic germ layers. They may be benign or malignant, may arise in any part of the body, and are usually found in midline structures. Thoracic teratomas usually present as an anterior mediastinal mass. Ovarian teratomas present as an abdominal mass often with symptoms of torsion, bleeding, or rupture. Retroperitoneal teratomas may present as a flank or abdominal mass.
Mature teratomas usually contain well-differentiated tissues and are benign, whereas immature teratomas contain varying degrees of immature neuroepithelium or blastemal tissues. Immature teratomas can be graded from 1 to 3 based on the amount of immature neuroglial tissue present. Tumors of higher grade are more likely to have foci of yolk sac tumor. Malignant germ cell tumors usually contain frankly neoplastic tissues of germ cell origin (i.e., yolk sac carcinoma, embryonal carcinoma, germinoma, or choriocarcinoma). Yolk sac carcinomas produce α-fetoprotein (AFP), whereas choriocarcinomas produce β-human chorionic gonadotropin (BHCG), resulting in elevation of these substances in the serum, which can serve as tumor markers. In addition, germinomas can also produce elevation of serum BHCG but not to the levels associated with choriocarcinoma.
Sacrococcygeal Teratoma
Sacrococcygeal teratoma usually presents as a large mass extending from the sacrum in the newborn period. Diagnosis may be established by prenatal US. In fetuses with evidence of hydrops and a large sacrococcygeal teratoma, prognosis is poor; thus, prenatal intervention has been advocated in such patients. The mass may be as small as a few centimeters in diameter or as massive as the size of the infant (Fig. 39-39). The tumor has been classified based on the location and degree of intrapelvic extension. Lesions that grow predominantly into the presacral space often present later in childhood. The differential diagnosis consists of neural tumors, lipoma, and myelomeningoceles.
Sacrococcygeal teratoma in a 2-day-old boy.
Most tumors are identified at birth and are benign. Malignant yolk sac tumor histology occurs in a minority of these tumors. Complete resection of the tumor as early as possible is essential. The rectum and genital structures are often distorted by the tumor but usually can be preserved in the course of resection. Perioperative complications of hypothermia and hemorrhage can occur with massive tumors and may prove lethal. This is of particular concern in small, preterm infants with large tumors. The cure rate is excellent if the tumor is excised completely. The majority of patients who develop recurrent disease are salvageable with subsequent platinum-based chemotherapy.
Liver Tumors
More than two thirds of all liver tumors in children are malignant. There are two major histologic subgroups: hepatoblastoma and hepatocellular carcinoma. The age of onset of liver cancer in children is related to the histology of the tumor. Hepatoblastoma is the most common malignancy of the liver in children, with most of these tumors diagnosed before 4 years of age. Hepatocellular carcinoma is the next most common, with a peak age incidence between 10 and 15 years. Malignant mesenchymomas and sarcomas are much less common but constitute the remainder of the malignancies. The finding of a liver mass does not necessarily imply that a malignancy is present. Nearly 50% of all masses are benign, and hemangiomas are the most common lesion.
Most children with a liver tumor present with an abdominal mass that is usually painless, which the parents note while changing the child's clothes or while bathing the child. The patients are rarely jaundiced but may complain of anorexia and weight loss. Most liver function tests are normal. AFP levels are increased in 90% of children with hepatoblastomas but much less commonly in other liver malignancies. Radiographic evaluation of these children should include an abdominal CT scan to identify the lesion and to determine the degree of local invasiveness (Fig. 39-40). For malignant-appearing lesions, a biopsy should be performed unless the lesion can be completely resected easily. Hepatoblastoma is most often unifocal, whereas hepatocellular carcinoma is often extensively invasive or multicentric. If a hepatoblastoma is completely removed, the majority of patients survive, but only a minority of patients have lesions amenable to complete resection at diagnosis.
Computed tomography of the abdomen showing a hepatocellular carcinoma in a 12-year-old boy.
A staging system based on postsurgical extent of tumor and surgical resectability is shown in Table 39-5. The overall survival rate for children with hepatoblastoma is 70%, but is only 25% for hepatocellular carcinoma. Children diagnosed with stage I and II hepatoblastoma have a cure rate of greater than 90% compared to 60% for stage III and approximately 20% for stage IV. In children diagnosed with hepatocellular carcinoma, those with stage I disease have a good outcome, whereas stages III and IV are usually fatal. The fibrolamellar variant of hepatocellular carcinoma may have a better prognosis.
Table 39-5Staging of pediatric liver cancer
Table 39-5 Staging of pediatric liver cancer
Stage I: No metastases, tumor completely resected
Stage II: No metastases, tumor grossly resected with microscopic residual disease (i.e., positive margins); or tumor rupture, or tumor spill at the time of surgery
Stage III: No distant metastases, tumor unresectable or resected with gross residual tumor, or positive lymph nodes
Stage IV: Distant metastases regardless of the extent of liver involvement
Source: Douglass E, Ortega J, Feusner J, et al. Hepatocellular carcinoma (HCA) in children and adolescents: results from the Pediatric Intergroup Hepatoma Study (CCG 8881/POG 8945). Proc Am Soc Clin Oncol. 1994;13:A-1439.
The abdominal CT scan usually will determine the resectability of the lesion, although occasionally this can only be determined at the time of exploration. Complete surgical resection of the tumor is the primary goal and is essential for cure. For tumors that are unresectable, preoperative chemotherapy should be administered to reduce the size of the tumor and improve the possibility for complete removal. Chemotherapy is more successful for hepatoblastoma than for hepatocellular carcinoma. Areas of locally invasive disease, such as the diaphragm, should be resected at the time of surgery. For unresectable tumors, liver transplantation may be offered in select patients. The fibrolamellar variant of hepatocellular carcinoma may have a better outcome with liver transplantation than other hepatocellular carcinomas.
Injury is the leading cause of death among children older than 1 year. In fact, trauma accounts for almost half of all pediatric deaths, more than cancer, congenital anomalies, pneumonia, heart disease, homicide, and meningitis combined. Motor vehicle collisions are the leading cause of death in people age 1 to 19 years, followed by homicide or suicide (predominantly with firearms) and drowning. Unintentional injuries account for 65% of all injury-related deaths in children younger than 19 years. Each year, approximately 20,000 children and teenagers die as a result of injury in the United States. For every child who dies from an injury, it is calculated that 40 others are hospitalized and 1120 are treated in emergency departments. An estimated 50,000 children acquire permanent disabilities each year, most of which are the result of head injuries. Thus, the problem of pediatric trauma continues to be one of the major threats to the health and well-being of children.
Specific considerations apply to trauma in children that influence management and outcome. These relate to the mechanisms of injury, the anatomic variations in children compared to adults, and the physiologic responses.
Mechanisms of Injury
Most pediatric trauma is blunt. Penetrating injuries are seen in the setting of gun violence, falls onto sharp objects, or penetration by glass after falling through windows. Age and gender significantly influence the patterns of injury. Male children between 14 and 18 years of age are exposed to contact sports and gun violence and, in some jurisdictions, drive motor vehicles. As a result, they have a different pattern of injury than younger children, characterized by higher injury severity scores. In the infant and toddler age group, falls are a common cause of severe injury. Injuries in the home are extremely common. These include falls, near-drownings, caustic ingestion, and nonaccidental injuries.
The goals of managing the pediatric trauma patient are similar to those of adults and follow advanced trauma life support guidelines as established by the American College of Surgeons Committee on Trauma. Airway control is the first priority. In a child, respiratory arrest can proceed quickly to cardiac arrest. It is important to be aware of the anatomic differences between the airway of the child and the adult. The child has a large head, shorter neck, smaller and anterior larynx, floppy epiglottis, short trachea, and large tongue. The size of the endotracheal tube can be estimated by the formula (age + 16)/4. It is important to use uncuffed endotracheal tubes in children younger than 8 years in order to minimize tracheal trauma. After evaluation of the airway, breathing is assessed. It is important to consider that gastric distention from aerophagia can severely compromise respirations. A nasogastric tube should therefore be placed early during the resuscitation if there is no head injury suspected, or an orogastric tube should be placed in cases of head injury. Pneumothorax or hemothorax should be treated promptly. When evaluating the circulation, it is important to recognize that tachycardia is usually the earliest measurable response to hypovolemia. Other signs of impending hypovolemic shock in children include changes in mentation, delayed capillary refill, skin pallor, and hypothermia. IV access should be rapidly obtained once the patient arrives in the trauma bay. The first approach should be to use the antecubital fossa. If this is not possible, a cut-down into the saphenous at the groin can be performed quickly and safely. Intraosseous cannulation can provide temporary access in children up to 6 years old until IV access is established. Percutaneous neck lines should generally be avoided. Blood is drawn for cross-match and evaluation of liver enzymes, lipase, amylase, and hematologic profile after the IV lines are placed.
In patients who show signs of volume depletion, a 20 mL/kg bolus of saline or lactated Ringer's should be promptly given. If the patient does not respond to two boluses, blood should be transfused (10 mL/kg). The source of bleeding should be established. Common sites include the chest, abdomen, pelvis, extremity fractures, or large scalp wounds. These should be carefully sought. Care is taken to avoid hypothermia by infusing warmed fluids and using external warming devices.
Evaluation of Injury
All patients should receive an x-ray of the cervical spine, chest, and abdomen with pelvis. All extremities that are suspicious for fracture should also be evaluated by x-ray. Plain cervical spine films are preferable to performing routine neck CT scans in the child, as x-rays provide sufficient anatomic detail. But if a head CT is obtained, it may be reasonable to obtain images down to C2 since odontoid views in small children are difficult to obtain. In most children, it is possible to diagnose clinically significant cervical spine injuries using this approach while minimizing the degree of radiation exposure. Screening blood work that includes aspartate aminotransferase, alanine aminotransferase, and amylase/lipase is useful for the evaluation of liver and pancreatic injures. Significant elevation in these tests requires further evaluation by CT scanning. The child with significant abdominal tenderness and a mechanism of injury that could cause intra-abdominal injury should undergo abdominal CT scanning using IV and oral contrast in all cases. There is a limited role for diagnostic peritoneal lavage (DPL) in children as a screening test. Although focused abdominal US (FAST exam) is extremely useful in the evaluation of adult abdominal trauma, it is not widely accepted in the management of pediatric blunt abdominal trauma. In part this relates to the widespread use of nonoperative treatment for most solid-organ injuries. Thus a positive abdominal US scan would not alter this approach in a hemodynamically stable patient. However, FAST exam can be very useful in the child who needs to go emergently to the operating room for management of significant intracranial hemorrhage, to ensure that there is no intraabdominal source of bleeding.
Injuries to the Central Nervous System
The central nervous system (CNS) is the most commonly injured organ system and is the leading cause of death among injured children. In the toddler age group, nonaccidental trauma is the most common cause of serious head injury. Findings suggestive of abuse include the presence of retinal hemorrhage on funduscopic evaluation, intracranial hemorrhage without evidence of external trauma (indicative of a shaking injury), and fractures at different stages of healing on skeletal survey. In older children, CNS injury occurs most commonly after falls and bicycle and motor vehicle collisions. The initial head CT can often underestimate the extent of injury in children. Criteria for head CT include any loss of consciousness or amnesia to the trauma or inability to assess the CNS status as in the intubated patient. Patients with mild, isolated head injury (Glasgow Coma Scale [GCS] 14–15) and negative CT scans can be discharged if their neurologic status is normal after 6 hours of observation. Young children and those in whom there is multisystem involvement should be admitted to the hospital for observation. Any change in the neurologic status warrants neurosurgical evaluation and repeat CT scanning. In patients with severe head injury (GCS ≤8), urgent neurosurgical consultation is required. These patients are evaluated for intracranial pressure monitoring and for the need to undergo craniotomy.
Thoracic Injuries
The pediatric thorax is pliable due to incomplete calcification of the ribs and cartilages. As a result, blunt chest injury commonly results in pulmonary contusion, although rib fractures are infrequent. Diagnosis is made by chest radiograph and may be associated with severe hypoxia requiring mechanical ventilation. Pulmonary contusion usually resolves with careful ventilator management and judicious volume resuscitation. Children who have sustained massive blunt thoracic injury may develop traumatic asphyxia. This is characterized by cervical and facial petechial hemorrhages or cyanosis associated with vascular engorgement and subconjunctival hemorrhage. Management includes ventilation and treatment of coexisting CNS or abdominal injuries. Penetrating thoracic injuries may result in damage to the lung or in major disruption of the bronchi or great vessels.
Abdominal Injuries
In children, the small rib cage and minimal muscular coverage of the abdomen can result in significant injury after seemingly minor trauma. The liver and spleen in particular are relatively unprotected and are often injured after direct abdominal trauma. Duodenal injuries are usually the result of blunt trauma, which may arise from child abuse or injury from a bicycle handlebar. Duodenal hematomas usually resolve without surgery. Small intestinal injury usually occurs in the jejunum in the area of fixation by the ligament of Treitz. These injuries are usually caused by rapid deceleration in the setting of a lap belt. There may be a hematoma on the anterior abdominal wall caused by a lap belt, the so-called "seat belt sign" (Fig. 39-41A). This should alert the caregiver to the possibility of an underlying small bowel injury (Fig. 39-41B), as well as to a potential lumbar spine injury (Chance fracture).
Abdominal computed tomography of patient who sustained a lap belt injury. A. Bruising is noted across the abdomen from the lap belt. B. At laparotomy, a perforation of the small bowel is identified.
The spleen is injured relatively commonly after blunt abdominal trauma in children. The extent of injury to the spleen is graded (Table 39-6), and the management is governed by the injury grade. Current treatment involves a nonoperative approach in most cases, even for grade IV injuries, assuming the patient is hemodynamically stable. This approach avoids surgery in most cases. All patients should be placed in a monitored unit, and type-specific blood should be available for transfusion. When nonoperative management is successful, as it is in most cases, an extended period of bed rest is prescribed. This optimizes the chance for healing and minimizes the likelihood of reinjury. A typical guideline is to keep the children on extremely restricted activity for 2 weeks longer than the grade of spleen injury (i.e., a child with a grade IV spleen injury receives 6 weeks of restricted activity). In children who have an ongoing fluid requirement or when a blood transfusion is required, exploration should not be delayed. At surgery, the spleen can often be salvaged. If a splenectomy is performed, prophylactic antibiotics and immunizations should be administered to protect against overwhelming postsplenectomy sepsis. The liver is also commonly injured after blunt abdominal trauma. A grading system is used to characterize hepatic injuries (Table 39-7), and nonoperative management is usually successful (Fig. 39-42). Recent studies have shown that associated injuries are more significant predictors of outcome in children with liver injuries than the actual injury grade. Criteria for surgery are similar to those for splenic injury and primarily involve hemodynamic instability. The intraoperative considerations in the management of massive hepatic injury are similar in children and adults. Renal contusions may occur after significant blunt abdominal trauma. Nonoperative management is usually successful, unless patients are unstable due to active renal bleeding. It is important to confirm the presence of a normal contralateral kidney at the time of surgery.
Table 39-6Grading of splenic injuries
Table 39-6 Grading of splenic injuries
Grade I: Subcapsular hematoma, <10% surface area capsular tear, <1 cm in depth
Grade II: Subcapsular hematoma, nonexpanding, 10%–50% surface area; intraparenchymal hematoma, nonexpanding, <2 cm in diameter; capsular tear, active bleeding, 1–3 cm, does not involve trabecular vessel
Grade III: Subcapsular hematoma, >50% surface area or expanding; intraparenchymal hematoma, >2 cm or expanding; laceration >3 cm in depth or involving trabecular vessels
Grade IV: Ruptured intraparenchymal hematoma with active bleeding; laceration involving segmental or hilar vessels producing major devascularization (>25% of spleen)
Grade V: Shattered spleen; hilar vascular injury which devascularizes spleen
Table 39-7Liver injury grading system
Table 39-7 Liver injury grading system
Grade I: Capsular tear <1 cm in depth
Grade II: Capsular tear 1–3 cm in depth, <10 cm length
Grade III: Capsular tear >3 cm in depth
Grade IV: Parenchymal disruption 25%–75% of hepatic lobe or 1–3 Couinaud's segments
Grade V: Parenchymal disruption >75% of hepatic lobe or >3 Couinaud's segments within a single lobe, injury to retrohepatic vena cava
Source: Reproduced with permission from Moore EE, Cogbill TH, Malangoni MA, et al. Organ injury scaling. Surg Clin North Am. 1995;75:293-303. Copyright Elsevier.
Abdominal computed tomography in a child demonstrating a grade III liver laceration (arrows).
One of the most exciting developments in the field of pediatric surgery has been the emergence of fetal therapy. In general terms, performance of a fetal intervention may be justified in the setting where a defect is present that would cause devastating consequences to the infant if left uncorrected. For the vast majority of congenital anomalies, postnatal surgery is the preferred modality. However, in specific circumstances, fetal surgery may offer the best possibility for a successful outcome. The decision to perform a fetal intervention requires careful patient selection, as well as a multidisciplinary center that is dedicated to the surgical care of the fetus and the mother. Patient selection is dependent in part on highly accurate prenatal imaging that includes US and MRI. Significant risks may be associated with the performance of a fetal surgical procedure, to both the mother and the fetus. From the maternal viewpoint, open fetal surgery may lead to uterine bleeding due to the uterine relaxation required during the procedure. The long-term effects on subsequent pregnancies remain to be established. For the fetus, in utero surgery carries the risk of premature labor and amniotic fluid leak. As a result, these procedures are performed only when the expected benefit of fetal intervention outweighs the risk to the fetus of standard postnatal care. Currently, open fetal intervention may be efficacious in certain instances of large congenital lung lesions with hydrops, large teratomas with hydrops, twin-twin transfusion syndrome, certain cases of congenital lower urinary tract obstruction, and myelomeningocele. This list of potential diagnoses that may benefit from a fetal intervention is significantly shorter than that of a decade ago, due in part to improvements in outcome of several diseases that are managed in the postnatal period, as well as the recognition of the relative lack of benefit of fetal surgery for many conditions.
Fetal Surgery for Lower Urinary Tract Obstruction
Lower urinary tract obstruction refers to a group of diseases characterized by obstruction of the distal urinary system. Common causes include the presence of posterior urethral valves and urethral atresia, as well as other anomalies of the urethra and bladder. The pathologic effects of lower urinary tract obstruction lie in the resultant massive bladder distention that occurs, which can lead to reflux hydronephrosis. This may result in oligohydramnios and cause limb contractures, facial anomalies (Potter sequence), and pulmonary hypoplasia. Carefully selected patients with lower urinary tract obstruction may benefit from vesicoamniotic shunting. By relieving the obstruction and improving renal function, fetal growth and lung development may be preserved.
Fetal Surgery for Congenital Diaphragmatic Hernia
Given the high mortality associated with the most severe cases of CDH, tremendous efforts have been undertaken to determine whether fetal intervention could improve the outcome of this disease. In 1990, Harrison and colleagues reported the first open fetal repair for CDH. The high morbidity of the open technique led to the development of fetal tracheal occlusion as a therapeutic approach. This was based on the observation that tracheal occlusion could lead to increased lung growth and reduction of the intrathoracic viscera in animal models. Tracheal occlusion can be achieved in utero by placement of clips that are removed at the time of delivery. Despite initial enthusiasm for this approach, a recent randomized trial that compared fetal tracheal occlusion with standard postnatal care for left-sided CDH showed no improvement in survival for patients treated with tracheal occlusion.
Fetal Surgery for Myelomeningocele
Myelomeningocele refers to a spectrum of anomalies in which portions of the spinal cord are uncovered by the spinal column. This leaves the neural tissue exposed to the injurious effects of the amniotic fluid, as well as to trauma from contact with the uterine wall. Nerve damage ensues, resulting in varying degrees of lower extremity paralysis as well as bowel and bladder dysfunction. Initial observations indicated that the extent of injury progressed throughout the pregnancy, which provided the rationale for fetal intervention. The current in utero approach for the fetus with myelomeningocele has focused on obtaining coverage of the exposed spinal cord. The efficacy of in utero treatment vs. postnatal repair was recently compared in a large multicenter trial and showed that prenatal surgery for myelomeningocele reduced the need for shunting and improved motor outcomes at 30 months but was associated with maternal and fetal risks. The results of this study have paved the way for the acceptance of in utero repair of myelomeningocele in certain centers with the experience and expertise to perform this procedure safely.
The EXIT Procedure
The EXIT procedure is an abbreviation for ex utero intrapartum treatment. It is used in circumstances where airway obstruction is predicted at the time of delivery, due to the presence of a large neck mass, such as a cystic hygroma or teratoma (Fig. 39-43), or congenital tracheal stenosis. The success of the procedure is dependent on the maintenance of utero-placental perfusion for a sufficient duration to secure the airway. To achieve this, deep uterine relaxation is obtained during a cesarean section under general anesthesia. Uterine perfusion with warmed saline also promotes relaxation and blood flow to the placenta. On average, between 20 and 30 minutes of placental perfusion can be achieved. The fetal airway is secured either by placement of an orotracheal tube or performance of a tracheostomy. Once the airway is secured, the cord is cut and a definitive procedure may be performed to relieve the obstruction in the postnatal period. In general terms, cystic neck masses such as lymphangiomas have a more favorable response to an EXIT procedure as compared to solid tumors, such as teratomas, particularly in premature infants.
The EXIT procedure (ex utero intrapartum treatment) in a 34-week gestation age baby with a large cervical teratoma. Intubation is being performed while the fetus is on placental support.
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