Small intestine
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Celiac disease or gluten intolerance/sensitivity: It is an autoimmune disorder induced by sensitivity to gliadin protein in gluten that causes gluten sensitive T -cells to attack intestinal villi . Gluten is a component of wheat, barley, rye, some medications, toothpastes, vitamin supplements and lip balms. It is prevalent in individuals with Northern European ancestry. Increased risk in HLA-DQA1 and HLA-DQB1. The disease presents with GI plus systemic manifestations beginning in early childhood such as chronic diarrhea, steatorrhea, bloating, abdominal pain, vomiting, weight loss, malabsorption, chronic fatigue, dermatitis herpetiformis, joint pain, iron deficiency anemia, osteoporosis, migraine, depression, ADHD, infertility, miscarriages, short stature and delayed puberty. Some patients may be clinically asymptomatic. Biopsy findings include infiltration of intestinal epithelium with lymphocytes, atrophy and flattening of the intestinal villi, loss of brush border and hyperplasia of intestinal crypts. Laboratory findings include elevated IgA anti-transglutaminase antibodies (most sensitive), anti-endomysial antibodies (most specific) and anti-gliadin antibodies. Patients with celiac disease are at increased risk of lymphomas and intestinal adenocarcinomas. Treatment is by avoiding gluten, supplementation for nutrient deficiencies and steroids or chemotherapy for resistant cases.
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Diarrhea: It is loose, watery stools more than three times a day. Acute diarrhea lasts for a few days; persistent diarrhea lasts between 2-4 weeks; chronic diarrhea lasts longer than 4 weeks. Medical conditions like hyperthyroidism, carcinoid syndrome, adrenocortical insufficiency, VIPoma, short bowel syndrome, IBD, IBS, ischemic colitis (bloody diarrhea with abdominal pain), lactose intolerance and medullary carcinoma thyroid can cause diarrhea. Medications like antibiotics, magnesium or calcium based antacids, PPIs, mannitol, lithium etc can cause diarrhea. Acidic pH of stool is seen in lactose intolerance.
Characteristics of different types of acute diarrhea
| Character | Condition seen |
| Non-inflammatory diarrhea with absence of leukocytes in stool | ETEC, B.cereus, S.aureus, Rotavirus, V.cholerae, Giardiasis, Cryptosporidium, Cl.perfringens |
| Inflammatory diarrhea with presence of leukocytes in stool | Non-typhi Salmonella, Shigella, Campylobacter, Shiga toxin producing E.coli, EIEC, Cl.difficile, Entamoeba histolytica, Yersinia enterocolitica |
| Diarrhea plus vomiting | Preformed bacterial toxin, viral illnesses |
| Pregnant women, unpasteurised cheese, raw milk | Listeriosis |
| Afebrile, abdominal pain and bloody diarrhea | Shiga toxin producing E.coli |
| Bloody diarrhea | Salmonella, Shigella, Campylobacter, shiga toxin producing E.coli, E.histolytica, Yersinia, Cl.difficile |
| Camping | Giardia |
| Fried rice | Bacillus cereus |
| Raw or improperly cooked ground beef, seed sprouts | E.coli O157:H7 |
| Raw milk | Salmonella, Campylobacter, Listeria, shiga toxin producing E.coli |
| Seafood, undercooked or raw shellfish | V.cholerae, V.parahaemolyticus |
| Daycare centers or old-age homes | Rotavirus, Cryptosporidium, Giardia, Shigella |
| Hospital admission or recent antibiotic use | Cl.difficile |
| Diarrhea with fever | Campylobacter, Salmonella, Shigella, Yersinia |
| Anal intercourse and proctitis | HSV, Chlamydia, Syphilis, Gonorrhea, Campylobacter, Salmonella, Shigella, E.histolytica, Giardia |
| Rice water stools | V.cholerae |
| Recent travel | ETEC, E.histolytica |
| HIV | Cryptosporidium, Isospora, Microsporidia, CMV, M.avium intracellulare, Listeria |
- Appendicitis: It is inflammation of the appendix. Appendicitis is more common in children and young adults. Luminal obstruction of any cause like fecaliths (hard fecal material) or lack of fibre in diet or lymphoid hyperplasia, lead to blockage of secretions and superimposed bacterial overgrowth and infection. Resulting inflammation can weaken the appendiceal wall leading to perforation in some cases. Few cases may not have any luminal obstruction but instead ischemia may cause wall damage. Classic clinical presentation is periumbilical pain (referred pain) that shifts to the right iliac fossa (peritoneal, parietal pain) , nausea, vomiting and loss of appetite. Fever may be present and rising fever is suggestive of peritonitis or impending appendiceal rupture. Histology shows local infiltration with neutrophils. Symptoms may vary with position of the appendix e.g. dysuria and increased frequency of urination is seen in pelvic appendicitis. Physical examination shows tenderness at the McBurney point which is located in the right iliac fossa, 2/3rd of the distance from the umbilicus, on an imaginary line drawn between the umbilicus and right anterior superior iliac spine. It corresponds to the base of the appendix in most patients. Rovsing sign may be positive, which includes pain felt in the right lower quadrant on palpation in the left lower quadrant and it results from peritoneal inflammation. Rigidity is seen in perforated appendix. Complications of acute appendicitis include gangrene and perforation with peritonitis. Laboratory findings include raised WBC count with neutrophil leukocytosis, elevated CRP and ESR. Ultrasound is preferred in children and pregnant women to avoid radiation exposure and shows enlarged, non-compressible appendix with periappendicular fluid . CT scan with contrast is the investigation of choice in suspected appendicitis and shows an inflamed appendix. Wall thickening and periappendiceal fat stranding are also seen. MRI can be used if clinical suspicion is high but routine investigations are inconclusive. Diagnostic laparoscopy for suspected appendicitis is recommended for young women (if diagnosis unclear to differentiate from PID or ectopic pregnancy), the elderly, or other patients with unclear pathology because of its broader diagnostic ability. Treatment is by laparoscopic (preferred) or open appendicectomy along with supplemental antibiotic therapy. IBD involving the appendix may clinically mimic appendicitis. It can be differentiated by biopsy findings.
- IBS or irritable bowel syndrome: It is a functional disorder characterized by recurrent abdominal pain >once/week lasting >6 months along with change in the frequency or form of stool, diarrhea and constipation. Symptoms improve after defecation and are exacerbated by emotional stress or eating. It is more common in young women. Stools may become mucousy but not bloody. Constipation predominant IBS is caused by functional obstruction to defecation from pelvic floor dys-synergia, manifested as paradoxical anal contraction on straining. Diarrhea predominant IBS can be differentiated from IBD by fecal calprotectin levels which are normal in IBS. Some cases of IBS may be post-infectious. Intestinal microbiomes may be altered in IBS. Levels of serotonin in the gut and TNF alpha in the blood may be elevated. Dietary modifications, increasing fibre intake, probiotics, biofeedback, managing stress, lubiprostone and linaclotide for constipation, 5HT3 antagonists like alosetron or ondansetron in diarrhea, loperamide and antidepressants are used as therapy.
- Intussusception: It is the telescoping of a segment of intestine into another causing obstruction. The telescoped segment is called intussusceptum while the receiving segment is called intussuscipiens. It is more common in small children usually due to lymphoid hyperplasia from viral infections and following Rotavirus vaccination. Older patients have underlying masses like lipomas or leiomyomas as the leading point of the intussusception. Other associated conditions include cystic fibrosis, polyps, adhesions, Henoch Schonlein purpura and endometriosis. Most common type is ileocaecal followed by ileo-ileal and colo-colic. Clinical features include intermittent abdominal pain, vomiting, passing mucus and blood tinged stools (red currant-jelly). Children may pull legs up to the chest from pain. Perforation and peritonitis may occur. A “sausage shaped” mass can be palpated in the abdomen most commonly in the right hypochondrium with an empty right lower quadrant called Dance sign. Ultrasound is preferred in children and CT scan in adults. Imaging shows target or doughnut sign with a hyper-echoic core surrounded by a hyp-echoic edematous bowel. Treatment is by barium or air enema. Non-reducible cases may be treated by surgical reduction. Treatment of intussusception in adults is always by exploratory laparotomy or laparoscopy followed by resection of lead point masses.
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