ADAM Health Encyclopedia

Toxic megacolon

Definition

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.

Alternative Names

Causes

This is a complication of inflammatory bowel disease, such as ulcerative colitis and Crohn’s disease, and some infections of the colon. Other forms of megacolon exist and can be congenital (present since birth) or associated with some forms of constipation.

Symptoms

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

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

Exams and Tests

The rapid widening (dilation) of the colon distinguishes it 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 abdominal tenderness and possible loss of bowel sounds.

Tests:

• Abdominal x-ray shows widening of the colon.
• Complete blood count may show an increased white blood cell count.
• Blood electrolytes may reveal a low potassium level or signs of dehydration.

Treatment

The goal of treatment is to reduce the size of the colon and to prevent it from becoming wider. If this is not done, or if the patient does not improve within 24 hours, a colectomy (surgical removal of all or part of the colon) is needed.

Fluids and electrolytes will be given to help prevent dehydration and shock.

The underlying process that leads to megacolon should be treated first. However, this condition is often life-threatening and cannot be reversed with medical therapy. Thus, surgery to remove the colon will be necessary in the majority of cases.

If the toxic megacolon is the result of active inflammatory bowel disease, corticosteroids may help reduce the inflammatory reaction.

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

Outlook (Prognosis)

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

Possible Complications

• Sepsis
• Shock
• Perforation of the colon

When to Contact a Medical Professional

Go to the emergency room or call the local emergency number (such as 911) if severe abdominal pain develops -- particularly if it is accompanied by fever, rapid heart rate, tenderness when the abdomen is pressed, bloody diarrhea, frequent diarrhea, or painful bowel movements.

Prevention

Treatment of the underlying disease is important in preventing toxic megacolon.

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