Crohn's Disease - Introduction

Inflammatory bowel disease (IBD) is a general term that includes two main disorders:

These two diseases are related, but they are considered separate disorders with somewhat different treatment options. The basic distinctions between UC and CD are location and severity. However, as many as 10% of patients with IBD have features and symptoms that match the criteria for both disorders, at least in the early stages. (This is called indeterminate colitis.)

Crohn's disease, also called regional enteritis, is a chronic inflammation of the intestines which is usually found in the terminal portion of the small intestine, the ileum. Ulcerative colitis is a similar inflammation of the colon, or large intestine. These and other IBDs (inflammatory bowel disease) have been linked with an increased risk of colorectal cancer.

Crohn's Disease. Crohn's disease is an inflammation that extends into the deeper layers of the intestinal wall. It is found most often in the area bridging the small and large intestines, specifically in the ileum and the cecum, sometimes referred to as the ileocecal region. Less often, Crohn's disease develops in other parts of the gastrointestinal tract, including the anus, stomach, esophagus, and even the mouth. It may affect the entire colon or form a string of connected ulcers in one part of the colon. It may also develop as multiple scattered clusters of ulcers throughout the gastrointestinal tract, skipping healthy tissue in between.

Ulcerative Colitis. Ulcerative colitis is an inflammatory disease of the large intestine. Ulcers form in the inner lining, or mucosa, of the colon or rectum, often resulting in diarrhea, which may be accompanied by blood and pus. The inflammation is usually most severe in the sigmoid and rectum and typically diminishes higher in the colon. The disease develops uniformly and consistently until, in some people, the colon becomes rigid and foreshortened. [For more information, see In-Depth Report #69: Ulcerative colitis.]