Atlas of pathophysiology, 2 Edition

Part II - Disorders

Gastrointestinal Disorders

Diverticular Disease

In diverticular disease, bulging pouches (diverticula) in the GI wall push the mucosal lining through the surrounding muscle. Although the most common site for diverticula is in the sigmoid colon, they may develop anywhere, from the proximal end of the pharynx to the anus. Common sites include the duodenum, near the pancreatic border or the ampulla of Vater, and the jejunum.

Diverticular disease of the stomach is rare and is usually a precursor of peptic or neoplastic disease. Diverticular disease of the ileum (Meckel's diverticulum) is the most common congenital anomaly of the GI tract.

Diverticular disease has two clinical forms:

·         diverticulosis—diverticula present but asymptomatic

·         diverticulitis—inflamed diverticula; may cause potentially fatal obstruction, infection, or hemorrhage.

Age Alert

Diverticular disease is most prevalent in men over age 40 and persons who eat a low-fiber diet. More than half of patients older than age 60 have colonic diverticula.

Causes

·         Exact cause unknown

·         Diminished colonic motility and increased intraluminal pressure

·         Low-fiber diet

·         Defects in colon wall strength

Pathophysiology

Diverticula probably result from high intraluminal pressure on an area of weakness in the GI wall where blood vessels enter. Diet may be a contributing factor, because insufficient fiber reduces fecal residue, narrows the bowel lumen, and leads to high intra-abdominal pressure during defecation.

In diverticulitis, undigested food and bacteria accumulate in the diverticular sac. This hard mass cuts off the blood supply to the thin walls of the sac, making them more susceptible to attack by colonic bacteria. Inflammation follows and may lead to perforation, abscess, peritonitis, obstruction, or hemorrhage. Occasionally, the inflamed colon segment adheres to the bladder or other organs and causes a fistula.

Signs and symptoms

Diverticulosis

·         Asymptomatic

Mild diverticulitis

·         Moderate left lower abdominal pain

·         Low-grade fever

·         Leukocytosis

·         Nausea and vomiting

Severe diverticulitis

·         Nausea and vomiting

·         Left lower quadrant pain; abdominal rigidity

·         High fever, chills, hypotension, shock

·         Microscopic to massive hemorrhage

Chronic diverticulitis

·         Constipation, ribbonlike stools, intermittent diarrhea, abdominal distention

·         Abdominal rigidity and pain, diminished or absent bowel sounds, nausea, and vomiting

Diagnostic test results

·         Upper GI series reveals diverticulosis of the esophagus and upper bowel.

·         Barium enema reveals filling of diverticula, which confirms diagnosis.

·         Biopsy reveals evidence of benign disease, ruling out cancer.

·         Blood studies show an elevated white blood cell count and elevated erythrocyte sedimentation rate in diverticulitis.

Treatment

·         Liquid or bland diet, stool softeners, occasional doses of mineral oil

·         Analgesics, such as meperidine or morphine

·         Antispasmodics

·         Antibiotics

·         Exercise

·         Colon resection with removal of involved segment

·         Temporary colostomy if necessary

·         Blood transfusions if necessary

·         High-residue diet after pain has subsided

P.173

DIVERTICULOSIS OF COLON

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