Melena or black, tarry, and sticky stools with an offensive odor results from mild-upper GI bleeding. Fresh red blood passed per rectum is called hematochezia.
Causes of Hematochezia
Infarction of gut.
Irritable bowel syndrome is a common functional bowel disorder, especially in young and middle-aged adults. They present clinically in either of the three ways: with chronic abdominal pain and constipation (spastic colitis), chronic intermittent often painless watery diarrhea, or a combination of both. The basic pathology is altered intestinal motility. A good history, exclusion of the relevant causes, establishes a diagnosis.
Irritable Bowel Syndrome: Diagnosis
There should be at least a 12-week history of abdominal discomfort or pain, intermittent or continuous in last one year with two of the following once per week (Rome II criteria).
1. Pain relieved by defecation.
2. Change in bowel frequency.
3. Change in bowel consistency.
No evidence of inflammatory, neoplastic, metabolic, or anatomic pathology to explain the features.
Stools >3 per day or less than 3 per week.
Stools are loose and watery or hard and lumpy.
Incomplete evacuation, straining, or urgency.
Mucous in stools.
Bloating or feeling of abdominal fullness.
Look for other cause especially if
Stool for occult blood is positive.
There is history of weight loss.
There is fever.
Patient awakens at night with symptoms.
There are abnormal labs.
Inflammatory bowel disease IBD (also called Granulomatous colitis) includes Ulcerative Colitis and Crohn’s Disease. Both are associated with chronic diarrhea (bloody more common in ulcerative colitis) with bloating, cramping abdominal pain, occasional nausea, vomiting with weight loss and fatigue. They primarily affect the bowel, but have many extra-intestinal manifestations like arthritis (especially affecting the knees), liver disease, uveitis, and pyoderma gangrenosum (ulcerated and gangrenous skin lesions). In Volume II also see X-ray of ulcerative colitis in Figure 63, and Crohn’s disease in Figure 64, also see endoscopic appearance of Crohn’s disease in Figure 98 and ulcerative colitis in Figure 99. MRI of Crohn’s disease is shown in Figure 79.
Differences Between Ulcerative Colitis and Crohn’s Disease
chronic diarrhea and crampy pain
Common site of pain
Pain left lower abdomen
pain right lower abdomen
Rectum always involved
terminal ileum often involved
frequent (perianal skin tags)
Small intestinal obs.
Response to antibiotic
Granuloma on biopsy
Fistula and fissures
lead pipe appearance
Colon (back-wash ileitis)
mouth to anus
skip lesion (patchy involvement)
aphthous ulcers, cobble stone
Mucosa and submucosal
strictures, abscesses, sinus and and bleeding fistula formation
Antibody in serum
p-ANCA (perinuclear anti-neutrophilic antibody) +ve in two-third
ASCA (anti-saccharomyces cerevisiae antibody) +ve in half of the patients
In ulcerative colitis the treatment depends on the severity of disease. High-grade fever, tachycardia, anemia, orthostatic hypotension, and weight loss are systemic features suggestive of moderate to severe disease. A sudden change in stool pattern (constipation) may be an indication for development of toxic megacolon. Criteria of mild, moderate, and severe disease are subsequently given.
Severity of Ulcerative Colitis and Crohn’s Disease
Blood in stool
+ve or −ve
10% of body weight
(Moderate is in between mild and severe disease)
Patients with inflammatory bowel disease commonly have liver involvement which may take any form as shown in the following. The commonest being pericholangitis.
Occur in about 15% over course of disease.
Focal and post-necrotic necrosis.
Chronic active hepatitis.
Primary sclerosing cholangitis.
Amyloidosis and Hemosiderosis.
Extra-intestinal involvement in inflammatory bowel disease occurs in about 15% over course of disease.
Extra-Intestinal Involvement in IBD
Arthritis of large joints especially knees.
Uveitis and episcleritis.
Ankylosing spondylitis (may be associated).
Iron, B12, folic acid, zinc, calcium, magnesium, Vitamin K deficiency.
Thrombo-embolic events and DVT.
Gallstones and kidney stones.
Fissures and fistula in Crohn’s.
Nephrolithiasis (mostly uric acid in UC and calcium oxalate in CD).
Aphthous stomatitis in Crohn’s.
Autoimmune hemolytic anemia.
Risk Factors for Colorectal Cancer in Ulcerative Colitis
Extent of disease (highest with pancolitis).
Duration of disease and younger age of onset.
Family history of gut cancer or primary sclerosing cholangitis.
Surveillance colonoscopy should be done once every three years and earlier when other risk factors are present.
Diarrhea comes from the Greek word “dia,” meaning through and “rhein,” meaning to flow. It is increase in frequency, loose in consistency, and weight more than 200g per day or passage of loose or watery stools, three or more times per day. Pathophysiologically, it may be classified as follows.
• Secretory diarrhea: It is due to increased intestinal ion secretion or inhibition of normal active ion absorption. (Cholera, E. coli, VIPoma, medullary carcinoma of thyroid, carcinoid syndrome, Zollinger–Ellison syndrome, bile salts, villous adenoma). It does not respond to fasting.
• Inflammatory diarrhea: It is also called invasive diarrhea or dysentery and is associated with fever, abdominal pain, and blood with leukocytes in stool. Volume is usually <1L/24h. It is secondary to colonic damage and exudation of mucus, blood, and protein (ulcerative colitis, CD, microscopic colitis, radiation enteritis, malignancy). Infecting agents include shigella, salmonella, amebiasis, C. difficile, E. coli 0157:H7 toxin, ischemia, and CMV. Stool leukocytes is an inexpensive test to differentiate inflammatory versus non-inflammatory types.
• Non-Inflammatory diarrhea: It is watery, with nausea and vomiting, volume >1L/24h, secondary to small intestine disease. Norwalk and Rota virus, entrotoxins as in Giardia, Staph. aureus, cholera. E. coli, bile acid, laxatives, and malabsorption.
• Often two or more mechanisms may be present simultaneously.
• Malabsorption: It is said to be present when the fecal fat is >7–10g/24h (chronic pancreatitis, tropical sprue, Whipple’s disease, bacterial overgrowth, vagotomy, diabetes mellitus).
• Infections diarrhea: It is due to infectious agents, which are commonly giardia, entamoeba histolytica, salmonella typhi, cyclospora, while AIDS-related infections include cytomegalovirus and cryptosporidium.
• Motility disorders: May be associated with diabetic autonomic neuropathy, hyperthyroidism, irritable bowel syndrome.
Diarrhea can be acute (less than 14 days) or chronic (>two weeks but usually >one month). Chronic diarrhea may be inflammatory, osmotic (malabsorption), secretory, motility-related, or factitious. Take a detailed history in chronic diarrhea, try to determine the site of disease (small bowel, large bowel, liver, pancreas, and so on) and effect of diarrhea (dehydration, vitamin deficiency, iron deficiency, calcium deficiency, and so on) and the cause (endemic area in amoebiasis, weight loss with cancer, contact history in TB, features of liver disease, heart disease, HIV predisposition, lactose intolerance, gluten sensitivity, features of thyrotoxicosis, history of GI operation, and so on).
To determine the severity, site, cause, effect, and complications of disease:
Assess onset (what seemed to have precipitated it), duration, and severity of diarrhea.
Stool color, consistency, volume, and frequency. Bloody diarrhea suggests inflammation, infection, or tumor.
Ask about the presence of mucous, blood, and tenesmus (it suggests dysentery, that is, amoebiasis or shigellosis).
Fever, blood, and abdominal pain may suggest dysentery.
Recent travel (traveler’s diarrhea).
Unusual food ingestion (food poisonings).
Exposure to sick contacts or other people with same disease (cholera occurs in epidemics).
Drugs taken in the recent past (especially antibiotics causing C difficile infection).
Relation to fasting (osmotic diarrhea ceases with fasting and secretory does not).
Family history (CD or ulcerative colitis or GI cancer).
Sexual practices and social habits (HIV).
Ask about features of steatorrhea (stools which are loose, frothy, silvery, foul smelling, and difficult to flush), best seen in chronic pancreatitis.
Take history of weight loss (malignancy and TB or HIV).
Mushy stools appear oily are related to malabsorption.
Excessive flatus with diarrhea in CHO malabsorption.
Lactose intolerance is evident form history.
Nocturnal diarrhea or fecal soiling in autonomic neuropathy or sphincter dysfunction.
Incomplete evacuation in IBS.
Look for features of various deficiencies (especially in chronic diarrhea).
Night blindness and hyperkeratosis of skin, in Vitamin A deficiency.
Leuconychia due to hypoalbuminemia.
Paresthesia may be seen in vitamin deficiency, especially B12.
Muscle wasting, decreased growth, and delayed wound healing with hypoproteinemia.
Tetany, in hypocalcemia.
Rickets in children and osteomalacia in adults, with Vitamin D deficiency.
Koilonychia and angular stomatitis in iron deficiency.
Non-GI causes like thyrotoxicosis, diabetic autonomic neuropathy, and medullary carcinoma of thyroid are considered as a cause of chronic diarrhea when appropriate history is present.
Try to exclude infection by sending the stool for culture and demonstrating parasitic infestation.
Chronic liver disease and pancreatic causes are diagnosed by the history of such disease in the past with abnormal liver or pancreatic function tests.
Try to rule out inflammatory causes (e.g., UC and CD) and neoplastic causes by barium studies and endoscopic examination.
In any case of chronic diarrhea, a good history and examination may suggest the diagnosis or direct toward targeted investigations. It should also determine the severity, localize the disease to the anatomical site, pick up complications, and determine the associated deficiencies.
Causes of Chronic Diarrhea (Common Causes are Given in Italic Text)
Disease and Clue to the Diagnosis.
Giardiasis: weight loss and stool examination.
Chronicamoebiasis: endemic area, stool showing amoeba with ingested RBC.
Intestinal TB: history of contact, ileoceacel disease on barium biopsy oncolonoscopy.
Liver insufficiency: H/O liver disease and abnormal LFTs.
CD: extraintestinal manifestations, barium examination, and colonoscopy with biopsy.
Ulcerative colitis: chronic diarrhea with blood and extraintestinal manifestations, CT with contrast and colonoscopy and biopsy.
Drugs: history and clear relation.
Thyrotoxicosis: clinically hyperthyroid with low TSH and high free T4.
Celiac disease: sensitivity to gluten and biopsy with IgA anti-transglutamase.
Tropical sprue: endemic area and response to tetracycline and folic acid.
Carcinoma colon: recent altered bowel habit in an elderly proved on endoscopic biopsy.
Acute pancreatitis: severe abdominal pain and markedly raised serum amylase (chronic pancreatitis is intermittent with calcification of the pancreas with CT abdomen).
Bacterial overgrowth: intermittent diarrhea with predisposition to stasis or history of bowel operation.
Intestinal lymphoma: weight loss and lymphadenopathy.
Addison’s disease: pigmentation, hypotension with low AM cortisol.
Zollinger-Ellison syndrome: refractory ulcers with raised gastrin.
Carcinoid syndrome: episodic wheezing and flushing with raised 5 HIAA in urine.
Peutz-Jegher syndrome: oral pigmentation and intestinal polyposis.
Familial polyposis: barium or endoscopy.
Immunodeficiency: immunological tests.
Constrictive pericarditis: Kaussmaul’s sign, pulsus paradoxus, and echocardiography.
Autonomic neuropathy: long-standing diabetes.
Acute diarrhea is less than 14-day duration and usually due to infections or drugs. Contaminated food and water source is the commonest cause. If due to preformed toxins, vomiting may be more prominent or the only symptom.
Viruses: Rotavirus, Norwalk virus, and CMV.
Bacteria: Shigella, salmonella typhi, campylobacter, vibrio cholerae, E. coli.
Food poisoning: Salmonella, staph aureus, bacillus cereus, clostridium perfringens.
Drugs: Antibiotics, laxatives, magnesium-containing antacids, colchicine, digoxin, quinidine, alcohol, H2-receptor antagonists, lactose- or sorbitol-containing products.
Traveler’s diarrhea is commonly due to bacteria (over 80 percent), viruses (5 to 8 percent), and parasites (less than 10 percent). Prevention is with keeping good hygiene, regular hand washing, using bottled water, pasteurized milk, and well-cooked food with avoidance of raw fruits and vegetables and salads, and so on, from market places.
It may occur after the travel (makes you sorry you went). Most commonly E. coli.
Enterotoxins: Staphylococcus aureus, bacillus cereus, clostridium perfringens.
Bacteria: Shigella, salmonella species, enteroinvasive E. coli, Yersinia enterocolitica, and Aeromonas species.
Viruses: Rotavirus, Norwalk virus.
Protozoa: Giardia lamblia, Entamoeba histolytica.
Left-sided disease is associated with small volume mushy stools, urge to defecate, seldom foul-smelling, and occasionally, mixed with mucus, pus, or blood with gripping hypogastric or LIF/RIF pain, which subsides after an enema, a bowel movement, or the passage of flatus.
Organic diarrhea is sudden with a definable onset with daily occurrence; nocturnal symptoms; duration <3 months; weight loss >5kg; and average daily fecal weight exceeding 400g.
Examination in Diarrhea
Signs to identify cause, severity, or complications of the diarrhea.
Signs of dehydration (to judge the severity and need for resuscitation).
Look for rigidity, guarding, and tenderness (complication of perforation).
Joint involvement (inflammatory bowel disease and Whipples disease).
Look for signs of chronic liver disease.
Thyroid swelling in thyrotoxicosis and medullary carcinoma of thyroid).
Lymphadenopathy (lymphoma, AIDS).
Hyperpigmentation (Addison’s and Whipples disease).
Dermatitis (pellegra and dermatitis herpatiformis in celiac disease).
Operation (vagotomy, ileal resection with dumping syndrome).
Eyes (uveitis in inflammatory bowel disease, Reiter syndrome).
Anus (perianal skin tag in CD, patulous in advanced age, general weakness, or peripheral or central nerve involvement).
Signs of deficiency. (Vitamin A, B1, B2, B6, B12, C, D, K, Calcium, and protein. and so on).
Kaposi sarcoma in AIDS.
• Formed and brown are healthy or may be due to incontinence.
• Blood outside of a normal, formed stool is likely to be hemorrhoids, anal fissure, rectal tumor, or proctitis.
• Blood mixed with watery stool may be acute infectious diarrhea or IBD.
• A yellow pasty stool is characteristic of giardiasis.
• Fatty, greasy stool may be seen in malabsorption syndrome like chronic pancreatitis.
• Clear water with a solid, formed brown stool is likely to be mixed with urine or factitious diarrhea.
• Semi-formed or pasty brown stool with mucus suggests irritable bowel syndrome.
Investigations, procedures, or trials of therapy where diagnosis is not possible.
• Stool culture, stool analysis with occult blood, WBCs, and ova cyst.
• Stool for fat with Sudan stain.
• Clostridium difficile toxin and PCR for antibiotic-associated colitis.
• Ultrasound abdomen for liver, pancreas, and gallbladder disease.
• Thyroid function tests (serum calcitonin for medullary carcinoma thyroid).
• Fecal electrolytes, osmolality, osmotic gap (for osmotic or secretory process).
• Fecal pH is <5.3 in carbohydrate malabsorption.
• Endoscopy helps confirm antibiotic-associated colitis (pseudomembraneous colitis) or IBD and tumors. Upper GI endoscopy with small bowel biopsy is most useful in coeliac and lymphoma.
• Barium x-rays of the stomach, small intestine, and colon with chronic diarrhea for example, diverticulosis, CD, and ulcerative colitis and GI tumors, and so on.
• Lactoferrin latex agglutination is a rapid semi-quantitative test for fecal leukocyte detection, suggestive of invasive infectious diarrhea.
• Do stool C/S when fever >101°F; severe diarrhea; bloody stools; fecal leukocytes, or occult blood; or persistent diarrhea not treated with antibiotics is present.
• Serum antiendomysial antibody IgA assays to rule out celiac sprue.
• Tumor markers like CEA (carcinoembryonic antigen), CA 19–9 for carcinoma pancreas, and alpha-fetoprotein for hepatocellular carcinoma. Gastrin for Zollinger–Ellison syndrome. 24-hour urine for 5 GIAA for carcinoid.
• Trial of lactose-free diet.
• Trial of treatment for IBS.
• Trial of salazopyrine or asacol for IBD.
• Trial of wheat-free diet for celiac disease.
• Trial of anti-tuberculous treatment.
• PBG or ALA in urine for acute intermittent porphyria.