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the improvement in laparoscopic instruments and techniques has since paved the way for the management of malignant and benign diseases of the horseshoe kidney in the adult and pediatric population .
this particular congenital anomaly presents a challenge secondary to its anatomic position , association with aberrant vessels , and a bridge of renal tissue that connects the left and right renal moieties inferiorly .
we report our experience with laparoscopic heminephrectomy of the horseshoe kidney for benign disease , as well as review the literature and the technique .
a 56-year - old man was referred to the urology service with left flank pain , an episode of urinary tract infection and a nonfunctioning , left hydronephrotic moiety of a horseshoe kidney identified on abdominal sonography ( figure 1 ) and ct scan .
renal function was assessed by a radioisotope scan ( figure 2 ) , which demonstrated an obstruction to the flow of urine in the left kidney , with 0% differential function in the left kidney and 100% in the right .
a ct scan of the abdomen and pelvis demonstrated a markedly atrophic left renal kidney , with evidence of inflammatory phlegmon surrounding the atrophic kidney .
further evaluation of renal function with a radioisotope renal scan revealed 2% function of the left kidney and 98% function of the right . with clinical evidence of chronic pyelonephritis
after co2 insufflation of the peritoneal cavity , the left hemicolon is reflected along the line of toldt .
the ureter is identified medial to the psoas muscle and dissected cephalad to identify the renal isthmus .
then the isthmus is dissected circumferentially and divided with an endostapler ( figure 3 ) .
further dissection is performed medially to identify as many aberrant vessels as are present . these are individually clipped and divided .
the nephrectomy is completed after division of the ureter , and the kidney is morcellated within a lap sac ( cook , spencer , in ) .
both patients had an uneventful convalescence and were discharged home on the third postoperative day .
it occurs at an incidence between 1 in 400 and 1 in 800 , with a slight predominance in males .
while the majority of horseshoe kidneys go undiagnosed , the most common presenting symptoms are secondary to ureteropelvic junction ( upj ) obstruction , renal stones , or both .
upj obstruction , the most common complication of the horseshoe kidney , occurs at an incidence of 25% to 40% .
the cause of upj obstruction is believed to be the abnormal course of the ureter over the isthmus , high insertion of the ureter into the renal pelvis , and rarely , secondary to an anomalous blood supply to the isthmus crossing the upj .
finally , the anterior location of the renal pelvis also contributes to urinary stasis , infection , and the formation of stones , which can cause obstruction at the level of the upj .
traditionally , upj obstruction in a horseshoe kidney has been treated by open dismembered pyeloplasty in a functioning kidney or by open nephrectomy in a poorly or nonfunctioning moiety . with the advent of minimally invasive surgery in the last 2 decades , conditions associated with the horseshoe kidney
laparoscopic heminephrectomy for the horseshoe kidney is a safe and effective minimally invasive technique that was first described by reidl et al .
however , 3 factors are unique to the horseshoe kidney that make the laparoscopic approach challenging : its association with aberrant vessels , the isthmus , and the anatomic position .
familiarity with the anatomy and variations in the technique are essential for a successful outcome .
the arterial supply of the horseshoe kidney has been studied by janetschek et al in 6 postmortem horseshoe kidneys .
although this anatomical study was oriented to establish the risk of hemorrhage during a percutaneous nephrolithotomy , it is reflective of the arterial patterns encountered during laparoscopic nephrectomy .
in addition to normal renal arteries , accessory arteries originating from the great vessels entering the hilum and aberrant vessels entering directly into the poles of the kidneys and the isthmus were described .
radiographic imaging studies can play a vital role in the preoperative planning of heminephrectomy for horseshoe kidneys .
the use of magnetic resonance urography was described by mostafavi et al to evaluate upj obstruction .
this study , as an alternative to conventional urography , allows a better delineation of the anatomy .
they believe that this technique offers superior imaging compared with other imaging modalities , allowing simultaneous evaluation of renal anatomy and function . on the other hand , 3-dimensional computed tomographic angiography may offer the same information with less cost .
most recently , strauss et al using sonography reviewed 34 patients with horseshoe kidneys . 
the typical sonographic images of the horseshoe kidney include caudal renal position , malrotation with reversed longitudinal axis of each kidney , and anterior extrarenal pelves . 
as our case demonstrates , sonography can easily identify hydronephrosis ; however , it remains ineffective for identifying the isthmus or characterizing the blood supply to the horseshoe kidney .
finally , radioisotope scans can demonstrate the presence of obstruction ; however , like sonography , this imaging modality lacks the ability to identify the vasculature .
although all the case reports regarding heminephrectomy describe standard ct scans to evaluate the horseshoe kidney , donovan et al suggested that routine preoperative arteriography is essential to identify all vessels .
we believe that arteriography adds to the cost and subjects the patient to unnecessary radiation exposure and dye load leading to renal insufficiency or failure .
careful dissection of the isthmus and the renal pedicle should allow the surgeon to systematically identify the aberrant vessels , obviating the need for an arteriogram .
ao et al brought the isthmus outside the abdominal wall and divided it with electrocautery under direct vision .
depending on the thickness of the isthmus , the endostapler can be used several times . in case 1 , the isthmus was thick and required 3 loads of the endostapler to complete the division . during placement of the endostapler , one must be aware that the isthmus is supplied by vessels entering dorsally , and these must be avoided .
the use of ultrasonic shears , as well as a microwave coagulator device , has been described in dividing the isthmus .
whatever technique is used , it is important not to violate the collecting system of the contralateral kidney and to obtain adequate hemostasis .
finally , the conventional notion that lateral fixation of the lower pole should accompany division of the isthmus to protect the remaining kidney from developing ureteropelvic junction obstruction is no longer true . retroperitoneal laparoscopic nephrectomy , initially reported by gaur et al in 1993 , has become the technique of choice in most institutions .
in addition , it provides an optimal view of all the vessels . as the anterior surface of the horseshoe kidneys
is covered with posterior parietal peritoneum , it can become difficult to confine co2 to the retroperitoneal space while maintaining an adequate working space without inadvertently opening the peritoneum .
two cases of retroperitoneal nephrectomy for horseshoe kidneys have been reported by hemal et al .
it is a challenging approach and more experience is needed before it becomes the standard of care .
laparoscopic heminephrectomy is a feasible alternative in the surgical management of benign disease of the horseshoe kidney and may one day become accepted as the standard of care . as more surgeons continue to become familiar with laparoscopic surgery , open surgery for the horseshoe kidney for all indications may become obsolete . in addition , awareness of the differences in techniques unique to this congenital anomaly and familiarity with the anatomy will promote satisfactory results .
background and objective : minimally invasive surgery plays a definitive role in the management of complications associated with the horseshoe kidney ( hk ) . aberrant vessels , the renal isthmus , and renal ectopia are all unique features of this anomaly that make the laparoscopic approach a challenge . 
 we report our experience with this technique in 2 patients.methods:two patients with an hk were evaluated for recurrent urinary tract infection . in both cases , 
 the nonfunctioning renal moiety was demonstrated by renal scan . 
 a transperitoneal laparoscopic heminephrectomy was performed . 
 the endostapler device was used to divide the renal isthmus.results:the operative time was less than 3 hours . 
 blood loss was negligible . 
 no intraoperative complications occurred . 
 the hospital stay was 48 hours . 
 postoperative discomfort was minimal.conclusion:laparoscopic heminephrectomy is a safe and feasible approach for benign diseases of the hk . 
 the endostapler is a useful adjunct in the division of the renal isthmus .