Using Tests to Differentiate Between Crohn's Disease and Ulcerative Colitis |
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Endoscopy |
Ulcerative colitis almost always involves the lower left colon and rectum and can be diagnosed using sigmoidoscopy. Crohn's disease may require colonoscopy as well. Endoscopy often reveals ulcers, diseased regions that have a cobblestone-like appearance in Crohn's disease, but not in ulcerative colitis. |
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X-Rays (Barium Enema) or Computed Tomography Scans |
In ulcerative colitis, inflammation is usually evenly distributed on the surface lining of the intestine, and the bowel wall bleeds easily when touched with a swab. The pattern observed in Crohn's disease is usually one of scattered patches of ulcers that are deep, thick, and large. Crohn's disease produces pockets (fissures) or channels (fistulas). They do not occur with UC. In ulcerative colitis the ileum (the lower part of the small intestine) is often dilated while it is narrowed in Crohn's disease. |
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Laboratory Tests |
Tissue samples obtained from a patient with Crohn's disease may reveal granulomas, small collections of inflammatory cells. Granulomas may also be present in other conditions, however. Tissue samples should also be examined for the presence of cancerous cells. About 70% of tests for antibodies in people with UC will show perinuclear-staining antineutrophil cytoplasmic antibodies. Over 50% of Crohn's people have anti-Saccharomyces cerevisiae antibodies. Such tests are expensive and infrequently performed, but they may be useful in cases of uncertainty. |
Ruling Out Diseases Resembling Inflammatory Bowel Disease
Irritable Bowel Syndrome. Irritable bowel syndrome (IBS), also known as spastic colon, functional bowel disease, and spastic colitis, causes many of the same symptoms as inflammatory bowel disease. Bloating, diarrhea, constipation, and abdominal cramps are all symptoms of IBS. Irritable bowel syndrome is not caused by inflammation, however, and no fever or bleeding occurs. Behavioral therapy may be helpful in treating IBS. (Psychological therapy does not improve inflammatory bowel disease.)
Microscopic Colitis. Microscopic colitis causes chronic watery diarrhea, but the colon lining shows little or no signs of inflammation. It may be genetically linked to celiac sprue. Most patients can expect to improve.
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