Tests and diagnosis

By Mayo Clinic Staff

Your doctor will likely diagnose ulcerative colitis only after ruling out other possible causes for your signs and symptoms, including Crohn's disease, ischemic colitis, infection, irritable bowel syndrome (IBS), diverticulitis and colon cancer. To help confirm a diagnosis of ulcerative colitis, you may have one or more of the following tests and procedures:

  • Blood tests. Your doctor may suggest blood tests to check for anemia or infection. Tests that look for the presence of certain antibodies can sometimes help diagnose which type of inflammatory bowel disease you have, but these tests can't definitely make the diagnosis.
  • Stool sample. The presence of white blood cells in your stool indicates an inflammatory disease, possibly ulcerative colitis. A stool sample can also help rule out other disorders, such as those caused by bacteria, viruses and parasites. In particular, infection with the bacterium Clostridium difficile can be responsible for diarrhea, but it's also more common among people with ulcerative colitis. Your doctor can also check for a bowel infection, which is more likely to occur in people with ulcerative colitis.
  • Colonoscopy. This exam allows your doctor to view your entire colon using a thin, flexible, lighted tube with an attached camera. During the procedure, your doctor can also take small samples of tissue (biopsy) for laboratory analysis. Sometimes a tissue sample can help confirm a diagnosis.
  • Flexible sigmoidoscopy. In this procedure, your doctor uses a slender, flexible, lighted tube to examine the sigmoid, the last portion of your colon. The test may miss problems higher up in your colon and it doesn't give a full picture of how much of the colon has been affected. But, if your colon is severely inflamed, your doctor may perform this test instead of a full colonoscopy.
  • Barium enema. This diagnostic test allows your doctor to evaluate your entire large intestine with an X-ray. Barium, a contrast solution, is placed into your bowel using an enema. Sometimes air is added as well. The barium coats the lining, creating a silhouette of your rectum, colon and a portion of your small intestine. This test is rarely used anymore, and it can be dangerous because the pressure required to inflate and coat the colon can lead to rupture of the colon. For people with severe symptoms, flexible sigmoidoscopy combined with a CT scan is a better alternative.
  • X-ray. A standard X-ray of your abdominal area may be done to rule out toxic megacolon or a perforation if these conditions are suspected because of severe symptoms.
  • CT scan. A CT scan of your abdomen or pelvis may be performed if your doctor suspects a complication from ulcerative colitis or inflammation of the small intestine that might suggest Crohn's disease. A CT scan may also reveal how much of the colon is inflamed.
Oct. 10, 2012

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