Toxic Megacolon

TM may occur in patients suffering from inflammatory bowel disease or other types of colitis. Thus, patients typically report prior gastrointestinal illness and treatment consistent with risk factors for TM. They should be queried regarding the use of antimotility agents.

TM patients present with constitutive symptoms such as high fever, chills, tachycardia, volume depletion, and reduced levels of consciousness. Patients are acutely ill and often claim abdominal cramps, diarrhea with blood or constipation. A physical examination reveals painful abdominal distention and reduced bowel sounds. Diffuse abdominal rigidity and rebound tenderness indicate peritonitis and may be noted in the case of intestinal perforation. Here, septic shock and multiple organ failure may ensue [6].

In 1969, Jalan and colleagues defined diagnostic criteria for TM [7]. They are still used today and comprise the following:

• Radiographic evidence of non-obstructive dilatation of the ascending or transverse colon to >6 cm (to >5.5 cm in children [8])

Plus either three of the following:

• Fever (>38.5 °C)
• Tachycardia (>120/min)
• Leukocytosis (>10.5 x 103/μL)
• Anemia

As well as either one of the following:

• Dehydration
• Hypotension
• Reduced consciousness
• Electrolyte imbalances

Diagnostic measures should be undertaken accordingly.

• Plain radiography is usually sufficient to identify colonic distension. Nevertheless, computed tomography is more sensitive with regards to the detection of perforation, abscesses or ascending pylephlebitis [4] [9]. Additionally, images obtained by means of computed tomography may depict diffuse colonic wall thickening, edematous haustral folds separated by transverse mucosal ridges (accordion sign, requires use of contrast agents), and hyperemic mucosa over edematous submucosa (target sign) [3].
• Laboratory analyses of blood samples should be performed and may additionally reveal enhanced concentrations of inflammatory marker C-reactive protein and erythrocyte sedimentation rate. Hypoalbuminemia and hypokalemia are related to a poor prognosis. Analyses of stool samples are recommended [10].

Hematocrit, serum levels of electrolytes, and acid-base status should be assessed repeatedly in order to monitor a patient's response to therapy. At somewhat longer intervals, abdominal radiography should be repeated to evaluate the condition of the colon and the risk of perforation.

Toxic megacolon (TM) is a severe inflammatory disorder affecting parts of or the entire colon. This condition is defined as a non-obstructive dilatation of the colon to diameters exceeding 6 cm and concomitant symptoms of systemic toxicity [1]. TM may complicate cases of ulcerative colitis (up to 10%), Crohn disease (up to 5%), pseudomembranous colitis (up to 3%), and, less frequently, other types of colitis [2] [3]. It has been suggested that chemotherapeutics, narcotics, anticholinergic and antidiarrheal drugs, discontinuation of steroid administration, and diagnostic measures like colonoscopy may predispose colitis patients for TM, but scientific evidence supporting these hypotheses is scarce.

Mortality rates have been reported to amount to 19% and patients require immediate medical attention to increase their chances of survival. The underlying colitis needs to be treated and disturbances of fluid, electrolyte, and acid-base balance have to be corrected. At the same time, any medication interfering with peristalsis should be withdrawn. Colonic decompression or surgery may become necessary upon disease progression [4] [5].

1. Sheth SG, LaMont JT. Toxic megacolon. Lancet. 1998;351(9101):509-513.
2. Woodhouse E. Toxic Megacolon: A Review for Emergency Department Clinicians. J Emerg Nurs. 2016.
3. Autenrieth DM, Baumgart DC. Toxic megacolon. Inflamm Bowel Dis. 2012;18(3):584-591.
4. Gan SI, Beck PL. A new look at toxic megacolon: an update and review of incidence, etiology, pathogenesis, and management. Am J Gastroenterol. 2003;98(11):2363-2371.
5. Miniello S, Marzaioli R, Balzanelli MG, et al. Toxic megacolon in ulcerative rectocolitis. Current trends in clinical evaluation, diagnosis and treatment. Ann Ital Chir. 2014;85(1):45-49.
6. Dobson G, Hickey C, Trinder J. Clostridium difficile colitis causing toxic megacolon, severe sepsis and multiple organ dysfunction syndrome. Intensive Care Med. 2003;29(6):1030.
7. Jalan KN, Sircus W, Card WI, et al. An experience of ulcerative colitis. I. Toxic dilation in 55 cases. Gastroenterology. 1969;57(1):68-82.
8. Benchimol EI, Turner D, Mann EH, et al. Toxic megacolon in children with inflammatory bowel disease: clinical and radiographic characteristics. Am J Gastroenterol. 2008;103(6):1524-1531.
9. Imbriaco M, Balthazar EJ. Toxic megacolon: role of CT in evaluation and detection of complications. Clin Imaging. 2001;25(5):349-354.
10. Levine CD. Toxic megacolon: diagnosis and treatment challenges. AACN Clin Issues. 1999;10(4):492-499.