Health Encyclopedia

Toxic megacolon

Definition

Toxic megacolon occurs when swelling and inflammation spread into the deeper layers of your colon. As a result, the colon stops working and widens (dilates). In severe cases, the colon may rupture.

Alternative Names

Toxic dilation of the colon; Megarectum; Inflammatory bowel disease - toxic megacolon; Crohn disease - toxic megacolon; Ulcerative colitis - toxic megacolon

Causes

The term "toxic" means that this problem is very dangerous. Toxic megacolon may occur in people with an inflamed colon due to:

Ulcerative colitis, or Crohn disease that is not well controlled
Infections of the colon such as Clostridioides difficile
Ischemic bowel disease (ischemic colitis)

Other forms of megacolon include pseudo-obstruction, acute colonic ileus, or congenital colonic dilation. These conditions do not involve an infected or inflamed colon.

Symptoms

The rapid widening of the colon may cause the following symptoms to occur over a short period of time:

Painful, distended abdomen
Fever (sepsis)
Diarrhea (usually bloody)

Exams and Tests

The health care provider will perform a physical exam. Findings may include:

Tenderness in the abdomen
Reduced or absent bowel sounds

The exam may reveal signs of septic shock, such as:

Increased heart rate
Mental status changes
Rapid heart rate
Low blood pressure

The provider may order any of the following tests:

Abdominal x-ray, ultrasound, CT scan, or MRI scan
Blood electrolytes
Complete blood count

Treatment

Treatment of the disorder that led to toxic megacolon includes:

Steroids and other medicines that suppress the immune system
Antibiotics

If you have septic shock, you will be admitted to the intensive care unit (ICU) of the hospital. Treatment may include:

Breathing machine (mechanical ventilation)
Dialysis for kidney failure
Fluids given directly into a vein (IV)
Medicines to treat low blood pressure, infection, or abnormal blood clotting
Oxygen

If rapid colon widening is not treated, an opening or rupture can form in it. If the condition doesn't improve with medical treatment, surgery will be needed to remove part or all of the colon.

You may receive antibiotics to prevent sepsis (a severe infection).

Outlook (Prognosis)

If the condition does not improve, it can be fatal. Colon surgery is usually needed in such cases.

Possible Complications

Complications may include:

Perforation of the colon
Sepsis
Shock
Death

When to Contact a Medical Professional

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
Rapid heart rate
Tenderness when the abdomen is pressed
Abdominal distention

Prevention

Treating diseases that cause toxic megacolon, such as ulcerative colitis or Crohn disease, can prevent this condition.

References

Ananthakrishnan AN, Regueiro MD. Management of inflammatory bowel disease. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran's Gastrointestinal and Liver Disease: Pathophysiology/Diagnosis/Management. 11th ed. Philadelphia, PA: Elsevier; 2021:chap 116.

Efron JE. Large bowel: management of toxic megacolon. In: Cameron JL, Cameron AM, eds. Current Surgical Therapy. 14th ed. Philadelphia, PA: Elsevier; 2023:190-194.

Lichtenstein GR. Inflammatory bowel disease. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 127.

Thomas N, Wu AW. Large intestine. In: Walls RM, ed. Rosen's Emergency Medicine: Concepts and Clinical Practice. 10th ed. Philadelphia, PA: Elsevier; 2023:chap 81.

Review Date:10/20/2025
Reviewed By:Todd Eisner, MD, Private practice specializing in Gastroenterology in Boca Raton and Delray Beach, Florida at Gastroenterology Consultants of Boca Raton. Affiliate Assistant Professor, Florida Atlantic University School of Medicine. Review provided by VeriMed Healthcare Network. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

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