What is toxic megacolon?

Updated: Apr 03, 2019
  • Author: Ali Nawaz Khan, MBBS, FRCS, FRCP, FRCR; Chief Editor: Eugene C Lin, MD  more...
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Toxic megacolon is defined as a severe episode of colitis with segmental or total dilatation of the colon. It is typically a complication of ulcerative colitis, but it may be a complication of Crohn disease, antibiotic-related pseudomembranous colitis, and other colitides. Pathologically, acute fulminant colitis is associated with neuromuscular degeneration and a rapid and extensive colonic dilatation. [3, 4, 5, 6, 7, 8, 9, 10] (See the images below.)

Double-contrast barium enema studies in a 44-year- Double-contrast barium enema studies in a 44-year-old man known to have long history of ulcerative colitis. Images show total colitis and extensive pseudopolyposis.
A 22-year-old man presented with abdominal pain, p A 22-year-old man presented with abdominal pain, passage of blood and mucus per rectum, abdominal distention, fever, and disorientation. Findings from sigmoidoscopy confirmed ulcerative colitis. Abdominal radiographs obtained 2 days apart show mucosal edema and worsening of the distention in the transverse colon. The patient's clinical condition deteriorated over the next 36 hours despite steroid and antibiotic therapy, and the patient had to undergo a total colectomy and ileostomy.

Patients with toxic megacolon often present in the emergency department as having abdominal distention superimposed on chronic or acute diarrhea. The diagnosis should be considered in all such patients. The diagnosis is usually based on thorough clinical history taking and physical examination combined with plain abdominal radiography. [11, 12, 13, 14]

Computed tomography (CT) scanning has a limited role, although it better depicts the anatomic detail of transmural disease, mesenteric involvement, and intraperitoneal complications of inflammatory bowel disease. [16] Ultrasonography and radionuclide studies also have a limited role, if any.

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