Crohn’s Disease - COMPLICATIONS

Posted by Alex

INTESTINAL COMPLICATIONS

Rectal bleeding is a common manifestation of both UC and CD. In UC the superficial inflammation induces capillary hemorrhage, manifested as bright red coating of stool or blood-tinged mucopus. In severe UC the bleeding can be more prominent and on rare occasions is profuse. Iron deficiency anemia is a common secondary association due to the chronic blood loss. In CD, hemorrhage may be profuse as a result of deeper inflammation and ulceration into larger vessels. Recurrent bleeding occurs in a small subset of patients with CD and is rarely the single indication for surgery.

Toxic megacolon, once thought to occur only with UC, also occurs in CD and infectious colitis. Toxic megacolon develops in seriously ill individuals when transmural inflammation extends into the muscular layer, thinning the intestinal wall. The entire colon, or segments of the colon, can dilate as a result of disruption of the neural and muscular elements that maintain normal tone. Dilatation of the diameter of the colon on a plain abdominal radiograph to > 6 cm, associated with clinical symptoms of increasing abdominal pain, distention, rebound tenderness, and signs of fever, tachycardia, and dehydration, indicates the condition. Even without prominent dilatation, similar symptoms and signs are sufficient to diagnose severe colitis with an identical risk of perforation and the hazard of peritonitis. Precipitating circumstances include severe colitis, instrumentation with barium studies or endoscopic procedures in severe inflammation, potassium depletion, anticholinergic medications, or narcotics, which are thought to reduce neuromuscular activity of the gut. Associated laboratory findings include leukocytosis, hypokalemia, anemia, and hypoalbuminemia.

Toxic megacolon should be anticipated in any patient with severe colitis, including segmental colitis, and these individuals require careful monitoring of vital signs, abdominal examinations for rebound tenderness, flat-plate abdominal radiographs for dilatation or free air, and laboratory studies to maintain an adequate hematocrit and electrolyte status. Toxic megacolon should be treated with intensive medical therapy, and failure to improve within 12 to 24 hours is an indication for colectomy. Early colectomy can prevent the morbidity and mortality of a perforation, which may exceed 20%.

CD, being transmural, is associated with additional intestinal complications. Thickened segments of inflamed bowel become fibrotic, and stricturing is common. Whereas bowel narrowing in UC is due to reversible muscular hypertrophy, the scarring in CD is largely irreversible. Transmural fissures extend into adjacent structures, producing an inflammatory mass, abscess, or fistula. Enteroenteric, -vesicular, -mesenteric, or cutaneous fistulas are common, as are rectovaginal fistulas, perianal fistulas, and abscesses.