Intestinal Complications of IBD

Some Complications of IBD Can Be Life-Threatening

Many people believe that inflammatory bowel disease (IBD) only causes diarrhea, but it also affects the large and small intestines in many different ways. The intestinal complications of IBD include abscesses, bowel obstruction, bowel perforation, colorectal cancer, fissures, fistulas, worsening of symptoms during the menstrual period, and toxic megacolon. Some of these complications of IBD, Crohn's disease, and ulcerative colitis can be life-threatening and require prompt treatment to prevent more serious disease.



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An abscess, which is more common in Crohn's disease than in ulcerative colitis, is an accumulation of pus at the site of an infection. It could occur inside the body where it can't be seen, such as in the intestinal wall, or externally, such as on the skin.

Internal abscesses may resolve with antibiotic treatment, but if not, they will need to be drained. This might be done by inserting a catheter through the skin to the abscess site. The catheter might be inserted in other ways, such as across the stomach wall. In some instances, surgery will be needed to drain the abscess.

Bowel Obstruction


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A bowel obstruction occurs when part of the small or large intestine is partially or fully blocked, preventing bodily waste from traveling through. An obstruction is usually accompanied by intense pain, vomiting, and constipation. In some cases, a nasogastric tube can help relieve symptoms, but surgery may be necessary to clear the obstruction.

Bowel Perforation


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The risk of the bowel developing a perforation (a hole) is rare, but it is a potentially fatal complication of IBD. Perforation is most common during the first flare-up of ulcerative colitis and in those whose intestinal walls have become very thin due to severe disease. A perforation is most commonly treated with surgery to repair the hole or even remove a portion of the intestine.

Colorectal Cancer

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People with IBD are at increased risk for colorectal cancer, particularly people who have had extensive ulcerative colitis for 8 to 10 years. People with Crohn's disease are also at risk, though there is less information available about the level of risk. Careful monitoring for colorectal cancer via a colonoscopy is necessary for anyone with IBD, but especially for those at the highest risk.


National Institutes of Health

A fissure is a painful tear in the anal canal that can cause bleeding. Most fissures will heal without surgery but instead with treatment such as topical creams and making sure bowel movements are passed without straining. Fissures that do not heal and become chronic may require surgery.


A fistula is an abnormal tunnel-like connection between two body cavities or between a body cavity and the skin. Fistulas tend to be more common in Crohn's disease than in ulcerative colitis, and, in fact, about 35 to 50 percent of people who have Crohn's disease may develop a fistula at some point during the course of their disease. Some fistulas may be treated by medications, but the more serious or extensive they are, the more likely they will require surgery.

Premenstrual Syndrome

Premenstrual Syndrome

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Some women who have IBD notice that their symptoms worsen during their menstrual period. Diarrhea and pain may increase prior to and during menses. The cause of these symptoms could be the increase in hormones during the menstrual cycle.

Toxic Megacolon

Toxic Megacolon

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Toxic megacolon is rare, but it is a life-threatening condition. Left untreated, toxic megacolon could lead to shock, perforation, or an infection in the abdomen or the blood. In some cases, it can be treated medically, but severe cases may require surgery.

7 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. What is an Abscess?

  2. Crohn's & Colitis Foundation. Abscess Drainage.

  3. Crohn's & Colitis Foundation. The Risk of Colorectal Cancer in Crohn's Disease and Ulcerative Colitis Patients.

  4. John Hopkins Medicine. Anal Fissures.

  5. Crohn's & Colitis Foundation. Fistula Removal.

  6. Lim SM, Nam CM, Kim YN, et al. The effect of the menstrual cycle on inflammatory bowel disease: a prospective study. Gut Liver. 2013;7(1):51-57. doi.10.5009/gnl.2013.7.1.51

  7. John Hopkins Medicine. Toxic Megacolon.

By Amber J. Tresca
Amber J. Tresca is a freelance writer and speaker who covers digestive conditions, including IBD. She was diagnosed with ulcerative colitis at age 16.