What Is Toxic Megacolon?

What Is Toxic Megacolon?

What Is Toxic Megacolon

Toxic megacolon occurs when swelling and inflammation spread to the deeper layers of the colon

Toxic megacolon is a rare and potentially life-threatening complication of severe inflammatory bowel diseases (IBDs) such as ulcerative colitis and Crohn’s disease or infection such as Clostridium difficile colitis.

Toxic megacolon occurs when swelling and inflammation spread to the deeper layers of the colon (the last section of the digestive tract), resulting in widening (dilatation) and decreased functioning of the colon. In severe cases, the colon may rupture. The condition increases the risk of infection throughout the body (sepsis), severe blood loss, shock, dehydration, and sometimes even death.

What causes toxic megacolon?

Toxic megacolon may occur in people with an inflamed colon due to:

  • Uncontrolled ulcerative colitis or Crohn’s disease
  • Ischemic colitis
  • Infections of the colon such as Clostridium difficile
  • Infection from a virus, bacterium, or even a parasite (less common):

What are risk factors for toxic megacolon?

Factors that can increase the risk of toxic megacolon include:

Other risk factors include diabetes, organ transplants, kidney failure, suppressed immunity, and chronic obstructive pulmonary disease.

Other types of megacolon do not involve colon inflammation or infection. They include:

  • Pseudo-obstruction
  • Acute colonic ileus
  • Congenital colonic dilation

How is toxic megacolon diagnosed?

Your doctor will examine you and ask about your current symptoms, medical history, and other conditions such as inflammatory bowel disease that tend to inflame the colon. Tests that may be ordered to confirm a diagnosis include:

Diagnostic criteria for toxic megacolon include:

  • Radiographic evidence of the dilation of the colon greater than 6 cm
  • At least three of the following:
    • Fever higher than 100.4 F (38 C)
    • Heart rate higher than 120 beats/min
    • Neutrophilic leukocytosis exceeding 10,500/micro/L
    • Anemia
  • At least one of the following:


Bowel regularity means a bowel movement every day. See Answer

How is toxic megacolon treated?

Toxic megacolon can be deadly if left untreated. Treatment of toxic megacolon may include:

  • Medications
    • Medications to treat the underlying condition or infection
    • Anti-inflammatory medicines and antibiotics to help treat or prevent infection
    • Steroids and other immune system suppressants such as infliximab or cyclosporine
  • Bowel rest and bowel decompression
    • Involves removing gas and substances filling the colon with the help of a suction tube
  • Intravenous (IV) fluids 
    • IV fluids and electrolytes to restore electrolyte levels and prevent dehydration and low blood pressure
  • Surgery
    • May be required to remove part or all of the colon if less invasive treatments fail to reduce the size of the toxic megacolon within 2-3 days

Your doctor may ask you to stop certain medications that could worsen toxic megacolon including opioids, anticholinergics, antidepressants, and antidiarrheal medications.

What are the complications of toxic megacolon?

Untreated toxic megacolon can result in severe complications such as:

The survival rate for well-treated toxic megacolon without perforation is higher than 95%, whereas it is about 80% with perforation.

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Medically Reviewed on 6/29/2022


Image Source: iStock image

Toxic Megacolon. Johns Hopkins Medicine: https://www.hopkinsmedicine.org/health/conditions-and-diseases/toxic-megacolon

Paul Frysh. What Is Toxic Megacolon? WebMD: https://www.webmd.com/ibd-crohns-disease/ulcerative-colitis/toxic-megacolon-overview

Toxic Megacolon. NIH: https://www.ncbi.nlm.nih.gov/books/NBK547679/