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DISEASES OF THE DIGESTIVE SYSTEM

DISEASES OF THE DIGESTIVE SYSTEM. Eman MS Muhammad. DISEASES OF THE INTESTINE. INTESTINAL DIVERTICULAE. Congenital diverticulae : Occur in the duodenum and the cecum. The wall consists of all the intestinal coats. Meckel's diverticulum:

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DISEASES OF THE DIGESTIVE SYSTEM

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  1. DISEASES OF THE DIGESTIVE SYSTEM Eman MS Muhammad

  2. DISEASES OF THE INTESTINE

  3. INTESTINAL DIVERTICULAE • Congenital diverticulae: • Occur in the duodenum and the cecum. • The wall consists of all the intestinal coats. • Meckel's diverticulum: • It is due to failure of obliteration of the proximal part of the vitello-intestinal duct which passes from the intestine to the umbilicus in the embryo. • The diverticulum forms a blind intestinal pouch 1-3 inch in length on the anti-mesenteric border of the lower ileum, 1-3 feet from the ileo-cecal valve.

  4. Complications: • Inflammation • Peptic ulceration if it contains heterotopic gastric mucosal tissue • Intussusception • Volvulus may occur if an intestinal loop gets twisted around the fibrous band which connects its tip to the umbilicus. • Tumor formation.

  5. The vitello-intestinal duct connects the fetal intestine to the yolk sac. It is normally closed by the 7th week of gestation.

  6. Meckel diverticulum. The blind pouch is located on the antimesenteric side of the small bowel.

  7. Acquired diverticulae: • Etiology: (1) Degenerative changes in the muscle coat in middle and old age causing weakness of the wall specially at the points of entry of the blood vessels and nerves (mesenteric border). (2) Increased intra-luminal pressuredue to gaseous distensioninconstipation.

  8. Sites: (1) Concave border of the second part of the duodenum. (2) Mesenteric border of the jejunum and ileum. (3) Descending and sigmoid colon. This is the commonest site. • The diverticula are multiple and occur on the convexity of the intestine opposite the mesenteric attachment and between the longitudinal muscle bands (taeniae).

  9. Pathological features: • The diverticula are out-pouching of the mucosa and submucosa through weak points in the muscle layer where it is pierced by the arteries. • They are multiple i.e. diverticulosis and vary in size but with an average diameter of 1 cm. • Their openings into the intestinal lumen are usually small. • Duodenal and jejunaldiverticulae contain fluid chyme and are silent. • Colonic diverticula contain hard fecal matter facilitating obstruction and inflammation.

  10. Complications: (1) Acute diverticulitis is the commonest complication and maylead toformation of a pericolic abscess. (2) Intestinal hemorrhage. (3) Perforation causing septic peritonitis usually localized. (4) Fistulae with the small intestine, bladder and abdominal wall. (5) Fibrosis results in chronic intestinal obstruction.

  11. HERNIA • Definition: • Protrusion of a part of a viscus usually an intestinal loop through an abnormal opening in the cavity in which it exists. • Types: (1) External hernia: Inguinal, femoral and umbilical hernia. (2) Internal hernia: e.g. diaphragmatic hernia.

  12. Etiology: (1) Local weakness at the site of formation either congenital or as a result of operation sear. (2) Increased intra- abdominal tension as in pregnancy, coughing and sudden muscular effort. • Complications: (1) Irreducibility (2) Strangulation (3) Inflammation (4) Obstruction

  13. Strangulated hernia

  14. ACUTE INTESTINAL OBSTRUCTION • Definition: • Sudden complete obstruction to the passage of the intestinal contents. • Types: (1) Simple obstruction (2) Strangulation (3) Paralytic ileus (4) Mesenteric vascular occlusion

  15. Effects: (1)Strong peristalsis above the obstruction. (2) Distension above the obstruction by the intestinal fluids. (3) Distension interferes with venous drainage from the intestine, venous congestion occurs with extravasation of blood in the intestinal wall, lumen and peritoneal cavity. (4) Bacteria penetrate the intestinal wall causing peritonitis.

  16. Strangulation: A. Strangulated Hernia: • Causes: (1) Free intestinal loop or omentum enters the hernial sac. (2) Fecal content accumulated in the herniated sac. • Effects: (1) Pressure on the herniated loop against the sharp edge of the hernial ring causes venous obstruction with the development of congestion and edema. (2) Arterial occlusion results in hemorrhagic infarction or gangrene. The wall becomes edematous, dark red and shows ecchymosis. (3) Peritonitis and toxemia.

  17. B. Intussusception: • Definition: • Invagination of a segment of the intestine (intussusceptum) into another adjacent distal segment (intussusceptien). • The condition commonly occurs in infants and children and rarely in adults.

  18. Causes: • Irregular peristalsis induced by: gastro-enteritis and inflammation of the intestinal lymphoid tissue in babies, irritating food, overfeeding, fasting, intestinal parasites, Meckel's diverticulum, polypoid tumors and rarely bilharzial polyps.

  19. Types: (1)Ileo-cecal: • Starts at the ileo-cecal valve where a segment of the small intestine invaginates into the large intestine and may reach the rectum. • This is the commonest type. (2)Enteric type (ileo-ileal): • A segment of the small intestine invagi­nates into another distal segment. • It may begin as enteric type and then the intussusceptum passes through the ileo-caecal valve. (3)Colo-colonic type: Is rare.

  20. Effects: (1) Compression of the veins causes congestion and edema in the intussusceptum. • Blood extravasated into the intestinal wall and lumen. (2) Obstruction of the arteries results in hemorrhagic infarction. (3) Blood and mucus per rectum.

  21. C. Volvulus: • Definition: • Twisting of a loop of intestine upon itself through 180° or more. • The condition occurs in the sigmoid colon and less commonly in the small intestine.

  22. Predisposing factor: (a) Long mesocolon. (b) Loaded sigmoid colon due to constipation (c) Peritoneal adhesions. • Effects: (a) Obstruction of the lumen and the blood vessels. (b) Hemorrhagic infarction, gangrene and peritonitis.

  23. Paralytic Ileus: • Definition: • A segment of the intestine loses its peristaltic movements. • Causes: (1) Peritonitis inhibiting the parasympathetic activity by the bacterial toxins. (2) Operative trauma to the intestine stimulating the sympathetic fibers. (3) Spinal cord injuries. • Effects: • Functional obstruction, intestinal dilatation above the obstruction, vomiting and dehydration.

  24. Mesenteric Vascular Occlusion: • Causes: (1) Arterial thrombosis caused by: (a) atherosclerosis (b) Embolism of the superior mesenteric artery. • The embolus is derived from cardiac vegetations, thrombi in the left atrium in congestive heart failure and thrombi in the left ventricle in myocardial infarction.

  25. Effects: • Hemorrhagic infarction of the intestine, gangrene andacuteintestinal obstruction. • General effects in acute intestinal obstruction: (1) Dehydration caused by: (a) Repeated vomiting (b) Fluid and blood accumulation in the intestinal lumen, wall and peritoneal cavity. • Dehydration causes shock. (2) Potassium loss due to vomiting causes myocardial damage. (3) Acute toxemia due to septic peritonitis.

  26. CHRONIC INTESTINAL OBSTRUCTION • Definition: • Gradual incomplete obstruction to the passage of the intestinal contents. • Causes: (1) Post-inflammatory stricture of the intestine caused by tuberculosis, amoebic and bacillary dysentery, diverticulitis, ulcerative colitis and regional enteritis. (2) Carcinoma of the colon specially of the annular type. (3) Peritoneal adhesions. (4) Hirschsprung's disease.

  27. Effects: (1) Intestinal hypertrophy and dilatation proximal to the obstruction. (2) Mucosal ulcers above the obstruction (stercoral ulcers) caused by trauma of the retained hard fecal masses and by bacterial invasion. (3) Predisposes to acute obstruction by impaction of feces or inflammatory edema at the point of narrowing.

  28. MALABSORPTION SYNDROMES • Suboptimal absorption of fats, vitamins, proteins, carbohydrates, electrolytes, minerals and water e.g. celiac disease, tropical sprue, Whipple disease and intestinal amyloidosis. • In celiac disease and tropical sprue the intestine shows enteritis and villous atrophy. • The patient suffers from diarrhea, steatorrhea and anemia. • Muscular, skeletal, endocrine, nervous and skin disorders result from vitamin and protein deficiencies.

  29. TUMOURS OF THE SMALL INTESTINE • Benign tumors: • Adenoma and leiomyoma are the commonest, but fibroma, neurofibroma and hemangioma may occur. • They may cause intussusception or volvulus.

  30. Malignant tumors: • Rare and include: (1) Adenocarcinoma: • Occurs with equal frequency in the duodenum, jejunum and ileum. • Grossly the tumor is either polypoid, ulcerative or infiltrating annular growth. • The tumor metastasizes to the peritoneum, mesenteric lymph nodes and the liver.

  31. (2) Carcinoid tumor (argentaffinoma): • Arises from the argentaffin cells in the appendix and distal ileum. • Gross picture: • A small firm submucosal nodule or plaque of golden yellow color. • Microscopic picture: • Sheets or groups of small polyhedral cells separated by loose vascular stroma. • The cells show brown to black granules with silver stains.

  32. Spread and effect: • One-fourth of carcinoids metastasizes to the peritoneum, lymph nodes and liver. • The liver metastasis release serotonin causing the carcinoid syndrome. • The syndrome consists of: (a) Flushing of the face (b) Diarrhea and watery stool (c) Bronchial spasm causing asthmatic-like attacks (d) Edema and ascites (e) Fibrous thickening and stenosis of the pulmonary and tricuspid valves. • The rest of carcinoids are locally malignant.

  33. (3) Malignant Lymphoma: • Usually of the non-Hodgkin's type. • Appears as a bulky soft mass. • The tumor metastasizes to the mesenteric lymph nodes, liver, lungs and bones.

  34. TUMOURS OF THE APPENDIX (1) Carcinoid tumor: • 70% of carcinoid tumors occur in the appendix. • The tumor appears as a small submucosal nodule at the tip of the appendix. • The tumor does not metastasize. (2) Adenocarcinoma. (3) Malignant lymphoma.

  35. TUMOURS OF THE LARGE INTESTINE • Benign tumors: • Adenoma, leiomyoma, fibroma, neurofibroma and haemangioma. • They are more common than those in the small intestine.

  36. (1)Tubular adenoma (adenomatous polyp): • Common in the rectum and colon in old age. • The tumors is single or multiple, sessile or pedunculated. • The tumor consists of tubules or glands lined by tall cells showing dysplasia. • Malignant change to adenocarcinoma may occur.

  37. A microscopic comparison of normal colonic mucosa on the left and that of an adenomatous polyp (tubular adenoma) on the right is seen here. The neoplastic glands are more irregular with darker (hyperchromatic) and more crowded nuclei. This neoplasm is benign and well-differentiated, as it still closely resembles the normal colonic structure.

  38. (2)Villous adenoma: • Common sites are the rectum and recto-sigmoid area. • The tumor is sessile, lobulated and 1-10 cm in diameter. • Histologically the tumor consists of finger-like papillae, each consists of a vascular connective tissue core covered by one or multiple layers of mucin secreting columnar cells. • The lesion is precancerous.

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