Ulcerative Colitis (cont.)

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How is the diagnosis of ulcerative colitis made?

The diagnosis of ulcerative colitis is suggested by the symptoms of abdominal pain, rectal bleeding, and diarrhea. As there is no gold standard for diagnosis, the ultimate diagnosis relies on a combination of symptoms, the appearance of the colonic lining at the time of endoscopy, histologic features of biopsies of the colonic lining, and studies of stool to exclude the presence of infectious agents that may be causing the inflammation.

  • Stool specimens are collected for analysis to exclude infection and parasites, since these conditions can cause colitis that mimics ulcerative colitis.
  • Blood tests may show anemia and an elevated white blood cell count or sedimentation rate (commonly referred to as "sed rate"). An elevated white blood cell count and sed rate both reflect ongoing inflammation, but may be elevated with any type of chronic inflammation including UC and Crohn's disease.
  • Other blood tests also may be checked including kidney function, liver function tests, iron studies, and C-reactive protein (another sign of inflammation).
  • There is some evidence that a stool test for a protein called calprotectin could be useful in identifying patients who would benefit from colonoscopy. Calprotectin seems to be a sensitive marker of intestinal inflammation meaning that it can be elevated before symptoms become severe and the signs of inflammation are unclear. In the right setting, particularly early in the course of IBD, elevated levels can suggest inflammatory bowel disease. This test alone, however, cannot distinguish between different diseases causing the inflammation so should be used with caution.
  • Confirmation of ulcerative colitis requires a test to visualize the large intestine. Flexible tubes inserted through the rectum (sigmoidoscopes and colonoscopes) permit direct visualization of the inside of the colon to establish the diagnosis and to determine the extent of the colitis. Small tissue samples (biopsies) can be obtained during the procedure to determine the severity of the colitis.
  • A barium enema X-ray also may indicate the diagnosis of ulcerative colitis. During a barium enema, a chalky liquid substance is administered into the rectum and injected into the colon. Barium is so dense that X-rays do not pass through it so the outline of the colon can be seen on X-ray pictures. A barium enema is less accurate and useful than direct visualization (sigmoidoscopy or colonoscopy) in the diagnosis of UC.

Knowledge of the extent and severity of the colitis is important in choosing among treatment options.

Some newer diagnostic modalities include video capsule endoscopy and CT/MRI enterography. Video capsule endoscopy (VCE) might be useful for detection of small bowel disease in patients with a diagnosis of UC with atypical features and who might be suspected of actually having Crohn's disease. With VCE, patients swallow a capsule that contains a camera that takes pictures while it travels through the intestines and sends the pictures wirelessly to a recorder. The pictures are then reviewed. In a study in 2007, VCE confirmed the presence of small bowel disease in about 15% of patients with ulcerative colitis with atypical features or unclassified inflammatory bowel disease, thus changing the diagnosis to Crohn's disease. This might be a useful diagnostic modality in this specific patient population.

CT and MRI enterography are imaging techniques which use oral liquid contrast agents consisting of PEG solutions or low concentration of barium to provide more adequate distension of the colon and small intestine. These have been reported to be superior to standard imaging techniques in the evaluation of small bowel pathology in patients with Crohn's disease. They have also been shown to provide adequate estimations of disease severity in ulcerative colitis (with some under- and overestimations).

Medically Reviewed by a Doctor on 7/16/2014

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