Atlas of pathophysiology, 2 Edition

Part II - Disorders

Gastrointestinal Disorders

Ulcerative Colitis

Ulcerative colitis is a continuous inflammatory disease that affects the mucosa of the colon and rectum. It invariably begins in the rectum and sigmoid colon, and commonly extends upward into the entire colon, rarely affecting the small intestine, except for the terminal ileum. Ulcerative colitis produces edema (leading to mucosal friability) and ulcerations. Severity ranges from a mild, localized disorder to a fulminant disease that may cause a perforated colon, progressing to potentially fatal peritonitis and toxemia. The disease cycles between exacerbation and remission.

Age Alert

Ulcerative colitis occurs primarily in young adults, especially women. Onset of symptoms seems to peak between ages 15 and 30 and between ages 55 and 65.

Causes

·   Unknown

·   May be related to abnormal immune response to food or bacteria such as Escherichia coli

Pathophysiology

Ulcerative colitis usually begins as inflammation in the base of the mucosal layer of the large intestine. The colon's mucosal surface becomes dark, red, and velvety. Inflammation leads to erosions that coalesce and form ulcers. The mucosa becomes diffusely ulcerated, with hemorrhage, congestion, edema, and exudative inflammation. Abscesses in the mucosa drain purulent pus, become necrotic, and ulcerate. Sloughing causes bloody, mucus-filled stools. As abscesses heal, scarring and thickening may appear in the bowel's inner muscle layer. As granulation tissue replaces the muscle layer, the colon narrows, shortens, and loses its characteristic pouches (hiatal folds).

Signs and symptoms

·   Weight loss

·   Foul-smelling stools

·   Recurrent bloody diarrhea, often containing pus and mucus (hallmark sign)

·   Abdominal cramping, fecal urgency

·   Weakness

Clinical Tip

Complications may include perforated colon, toxic megacolon, liver disease, stricture formation, colon cancer, anemia, or arthritis.

Diagnostic test results

·   Sigmoidoscopy confirms rectal involvement, specifically, mucosal friability and flattening and thick, inflammatory exudate.

·   Colonoscopy reveals extent of the disease, stricture areas, and pseudopolyps (not performed when the patient has active signs and symptoms).

·   Biopsy with colonoscopy shows areas of inflammation.

·   Barium enema reveals extent of the disease, detects complications, and identifies cancer (not performed when the patient has active signs and symptoms).

·   Stool specimen analysis reveals blood, pus, and mucus but no disease-causing organisms.

·   Serum potassium, magnesium, and albumin levels are decreased.

·   White blood cell count is decreased.

·   Hemoglobin level is decreased.

·   Prothrombin time is prolonged.

·   Elevated erythrocyte sedimentation rate correlates with severity of the attack.

·   Abdominal X-ray may reveal loss of haustration, mucosal edema, and absence of formed stool in the diseased bowel.

Treatment

·   Corticotropin and adrenal corticosteroids

·   Sulfasalazine

·   Antidiarrheals

·   Iron supplements

·   Liquid nutritional supplements

For severe disease

·   Total parenteral nutrition and nothing by mouth

·   I.V. fluids

·   Proctocolectomy with ileostomy

P.209

MUCOSAL CHANGES IN ULCERATIVE COLITIS

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