Toxic megacolon

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

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.

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
Ulcerative colitis
Ulcerative colitis is a condition in which the lining of the large intestine (colon) and rectum become inflamed. It is a form of inflammatory bowel ...
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Crohn disease
Crohn disease is a disease where parts of the digestive tract become inflamed. It most often involves the lower end of the small intestine and the be...
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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
Distended abdomen
A swollen abdomen is when your belly area is bigger than usual.
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Fever (sepsis)
Sepsis
Sepsis is an illness in which the body has a severe, inflammatory response to bacteria or other germs.
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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
Bowel sounds
Abdominal sounds are the noises made by the intestines.
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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
Abdominal x-ray
An abdominal x-ray is an imaging test to look at organs and structures in the abdomen. Organs include the liver, spleen, stomach, and intestines. T...
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Ultrasound
Abdominal ultrasound is a type of imaging test. It is used to look at organs in the abdomen, including the liver, gallbladder, pancreas, and kidneys...
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CT scan
An abdominal CT scan is an imaging test that uses x-rays to create cross-sectional pictures of the belly area. CT stands for computed tomography....
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MRI scan
An abdominal magnetic resonance imaging scan is an imaging test that uses powerful magnets and radio waves. The waves create pictures of the inside ...
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Blood electrolytes
Complete blood count
Complete blood count
A complete blood count (CBC) test measures the following:The number of white blood cells (WBC count)The number of red blood cells (RBC count)The numb...
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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.

Open References

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.

Digestive system - illustration
The esophagus, stomach, large and small intestine, aided by the liver, gallbladder and pancreas convert the nutritive components of food into energy and break down the non-nutritive components into waste to be excreted through the large intestine.
Digestive system
illustration
Toxic megacolon - illustration
Toxic megacolon is characterized by extreme inflammation and distention of the colon. Common symptoms are pain, distention of the abdomen, fever, rapid heart rate, and dehydration. This is a life-threatening complication that requires immediate medical treatment.
Toxic megacolon
illustration
Crohn disease - affected areas - illustration
The inflammation of Crohn disease is nearly always found in the ileocecal region. The ileocecal region consists of the last few inches of the small intestine (the ileum), which moves digesting food to the beginning portion of the large intestine (the cecum). However, Crohn disease can occur anywhere along the digestive tract.
Crohn disease - affected areas
illustration
Ulcerative colitis - illustration
Ulcerative colitis is categorized according to location. Proctitis involves only the rectum. Proctosigmoiditis affects the rectum and sigmoid colon. Left-sided colitis encompasses the entire left side of the large intestine. Pancolitis inflames the entire colon.
Ulcerative colitis
illustration
Digestive system organs - illustration
The digestive system organs in the abdominal cavity include the liver, gallbladder, stomach, small intestine and large intestine.
Digestive system organs
illustration

Digestive system - illustration
The esophagus, stomach, large and small intestine, aided by the liver, gallbladder and pancreas convert the nutritive components of food into energy and break down the non-nutritive components into waste to be excreted through the large intestine.
Digestive system
illustration
Toxic megacolon - illustration
Toxic megacolon is characterized by extreme inflammation and distention of the colon. Common symptoms are pain, distention of the abdomen, fever, rapid heart rate, and dehydration. This is a life-threatening complication that requires immediate medical treatment.
Toxic megacolon
illustration
Crohn disease - affected areas - illustration
The inflammation of Crohn disease is nearly always found in the ileocecal region. The ileocecal region consists of the last few inches of the small intestine (the ileum), which moves digesting food to the beginning portion of the large intestine (the cecum). However, Crohn disease can occur anywhere along the digestive tract.
Crohn disease - affected areas
illustration
Ulcerative colitis - illustration
Ulcerative colitis is categorized according to location. Proctitis involves only the rectum. Proctosigmoiditis affects the rectum and sigmoid colon. Left-sided colitis encompasses the entire left side of the large intestine. Pancolitis inflames the entire colon.
Ulcerative colitis
illustration
Digestive system organs - illustration
The digestive system organs in the abdominal cavity include the liver, gallbladder, stomach, small intestine and large intestine.
Digestive system organs
illustration

A Closer Look

Self Care

Tests for Toxic megacolon

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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Health Library

Toxic megacolon

Causes

Ulcerative colitis

Crohn disease

Symptoms

Distended abdomen

Sepsis

Exams and Tests

Bowel sounds

Septic shock

Abdominal x-ray

Ultrasound

CT scan

MRI scan

Complete blood count

Treatment

Outlook (Prognosis)

Possible Complications

When to Contact a Medical Professional

Prevention

References

Digestive system - illustration

Digestive system

Toxic megacolon - illustration

Toxic megacolon

Crohn disease - affected areas - illustration

Crohn disease - affected areas

Ulcerative colitis - illustration

Ulcerative colitis

Digestive system organs - illustration

Digestive system organs

Digestive system - illustration

Digestive system

Toxic megacolon - illustration

Toxic megacolon

Crohn disease - affected areas - illustration

Crohn disease - affected areas

Ulcerative colitis - illustration

Ulcerative colitis

Digestive system organs - illustration

Digestive system organs

A Closer Look

Self Care

Tests for Toxic megacolon

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