Toxic megacolon is a life-threatening complication of other intestinal conditions that causes rapid widening (dilation) of part of the large intestine within 1 to a few days.

Toxic megacolon occurs as a complication of inflammatory bowel disease, such as ulcerative colitis and Crohn’s disease, and infections of the colon. The term "toxic" means that this complication occurs with infection or inflammation.

This is not the same as other forms of megacolon, such as pseudo-obstruction, acute colonic ileus, or congenital colonic dilation. These conditions occur without infection or inflammation.

The rapid widening of the colon may cause the following symptoms:

• Abdominal pain
• Abdominal distention
• Abdominal tenderness
• Dehydration
• Fever
• Rapid heart rate
• Shock

The rapid widening (dilation) of the colon makes this different from other conditions, such as chronic constipation, that can widen the colon slowly and do not cause sudden, life-threatening symptoms.

A physical exam may reveal signs of septic shock. The doctor will notice tenderness in the abdomen and possible loss of bowel sounds.

Tests:

• Abdominal x-ray
• Blood electrolytes
• Complete blood count

Fluids and electrolytes will be given to help prevent dehydration and shock. The process that leads to megacolon can be treated medically first. However, this is usually not enough to reverse the megacolon.

If rapid widening is allowed to continue, an opening (perforation) can form in the colon. Therefore, most cases of toxic megacolon will require surgery, such as colectomy or removal of the entire colon.

Antibiotics may be given to prevent sepsis (a severe infection).

If the condition does not improve, there is a significant risk of death. In this situation, a colectomy is usually required.

• Perforation of the colon
• Sepsis
• Shock

Go to the emergency room or call the local emergency number (such as 911) if you develop severe abdominal pain -- especially if you also have:

• Bloody diarrhea
• Fever
• Frequent diarrhea
• Painful bowel movements
• Rapid heart rate
• Tenderness when the abdomen is pressed

Treatment of the underlying disease is important to prevent toxic megacolon.

Goldman L, Ausiello D. Cecil Textbook of Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007.

Su C, Lichtenstein GR. Ulcerative Colitis. In: Feldman M, Friedman LS, Brandt LJ, Sleisenger MH. Feldman: Sleisenger & Fordtran's Gastrointestinal and Liver Disease. 8th ed. Philadelphia, Pa: Saunders Elsevier; 2006:chap 109.

Marrero F. Severe complications of inflammatory bowel disease. Med Clin North Am. 2008;92:671-686.