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Inflammatory Bowel Disease

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Also known as: IBD; Crohn Disease; Ulcerative Colitis

What is inflammatory bowel disease?

Graphic of the colonInflammatory bowel disease (IBD) is a group of chronic disorders characterized by swollen and damaged tissues in the digestive tract. These conditions vary in severity from person to person and change over time. Periods of active disease may alternate with periods of remission. During a flare-up, a person may experience frequent bouts of watery and/or bloody diarrhea, abdominal pain, weight loss, and fever. Symptoms frequently diminish between these flare-ups. Many people may go through extended periods of remission between flare-ups. Photo source: NCI, Alan Hoofring

IBD affects one to three million people in the United States, according to the Centers for Disease Control and Prevention. The cause is not known, but some evidence points to a complex interaction of different factors, including a genetic predisposition and the presence of microbes in the digestive tract that trigger an abnormal immune response.

The most common inflammatory bowel diseases are Crohn disease (CD) and ulcerative colitis (UC). IBD affects both sexes, though UC is slightly more common in men and Crohn disease is more common in women. Both are most common in Caucasians and people of Ashkenazi Jewish origin who live in developed countries. However, IBD is increasing among non-Caucasians in North America.

Either form of IBD may affect anyone at any age, but the majority of cases are first diagnosed in people 14 to 24 years old, while a smaller number of cases are diagnosed between the ages of 50 and 70. In addition to gastrointestinal symptoms, children affected by CD or UC may experience delayed development and growth retardation. Those who are diagnosed with one of these conditions at a young age are also at an increased risk of developing colon cancer later in life.

Crohn Disease (CD)
Crohn disease can affect any part of the digestive tract from the mouth to the anus but is primarily found in the last part of the small intestine (the ileum) and/or in the colon (large intestine or bowel). With CD, bowel tissue may be affected in patches with normal tissue in between. Inflammation may penetrate deep into the tissues of the intestines/colon and form ulcers or fistulas. Fistulas are tunnels through the intestines that allow waste material to move into other areas. Other complications of CD may include bowel obstructions, anemia from bleeding tissues, tears in the anal skin, and infections. According to the Crohn's & Colitis Foundation of America, about two-thirds to three-quarters of people with Crohn disease will eventually require surgery, either to remove damaged sections of the intestines/colon or to treat an obstruction or fistula.

Ulcerative Colitis (UC)
Ulcerative colitis primarily affects the surface lining of the colon. Although the symptoms may be similar to those seen with CD, the tissue inflammation caused by UC is continuous rather than patchy. The inflammation usually starts from the anus and moves up the colon. Bloody diarrhea is more frequently seen with UC. The most serious complication of UC is toxic megacolon, a relatively rare acute condition in which a section of the colon becomes essentially paralyzed. Waste does not move through the section; it accumulates and dilates the colon. This can cause abdominal pain, fever, and weakness. It can become life-threatening if left untreated. People with toxic megacolon may need surgery to remove the large intestine.

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