Diagnosis:

There is no definitive diagnostic test for ulcerative colitis, although findings on biopsy and barium x-rays, as well as appearance during endoscopy enable a clear diagnosis in most cases. A doctor will diagnose ulcerative colitis based on medical history and physical examination, and the results of laboratory and endoscopic tests.

Laboratory Tests

• Blood tests are used for various purposes, including to determine the presence of anemia. An increased number of white blood cells or elevated levels of inflammatory markers such as C-reactive protein may indicate the presence of inflammation.
• A stool sample may be taken and examined for blood, infectious organisms, or both.

Endoscopy

Flexible Sigmoidoscopy and Colonoscopy. Flexible sigmoidoscopy and colonoscopy are standard endoscopic procedures for diagnosing ulcerative colitis. They are important in the diagnosis of both ulcerative colitis and Crohn's disease. Both procedures involve snaking a fiberoptic tube called an endoscope through the rectum to view the lining of the colon. The doctor may also insert instruments through the endoscope to remove a tissue sample for a biopsy.

• Sigmoidoscopy, which is used to examine the rectum and left (sigmoid) colon, lasts about 10 minutes and is done without sedation. It may be mildly uncomfortable, but it is not painful. Ulcerative colitis almost always involves the lower left colon and rectum. The doctor usually observes an evenly distributed inflamed surface lining the intestine, and the bowel wall bleeds easily when touched with a swab. If sigmoidoscopy indicates ulcerative colitis, the doctor may order a colonoscopy to confirm the diagnosis and to identify how much of the colon is involved.
• Colonoscopy allows a view of the entire colon and requires a sedative, but it is still performed on an outpatient basis. It is helpful for distinguishing between Crohn's disease and ulcerative colitis and in screening for colon cancer.

Patients diagnosed with ulcerative colitis may also need periodic endoscopies to evaluate their condition when symptoms flare up.

Barium Enema X-Ray

Sigmoidoscopy and colonoscopy are standard tests for diagnosing ulcerative colitis, but in some cases the doctor may order a double-contrast barium enema Swallowed barium passes into the small intestine and shows up on an x-ray image, which may reveal inflammation and other abnormalities.

A barium enema is a valuable diagnostic tool that helps detect abnormalities in the large intestine (colon). A barium enema, along with colonoscopy, remains standard in the diagnosis of colon cancer, ulcerative colitis, and other diseases of the colon.

Ruling out Diseases Resembling Ulcerative Colitis

Crohn's Disease. Diarrhea associated with ulcerative colitis tends to be more severe than diarrhea caused by Crohnâ ' s disease. Abdominal pain is more constant with Crohnâ ' s disease than with ulcerative colitis. Fistulas are common with Crohnâ ' s disease but very rare with ulcerative colitis. Endoscopy and imaging tests reveal more extensive involvement through the entire gastrointestinal tract with Crohnâ ' s disease than with ulcerative colitis. Ulcerative colitis does not involve the small intestine as Crohnâ ' s disease does

Irritable Bowel Syndrome. Irritable bowel syndrome (IBS), also known as spastic colon, functional bowel disease, and spastic colitis, causes some 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.)

Infectious Colitis. Infectious colitis appears very rapidly and painfully. Organisms can be identified in stool samples.

Intestinal Ischemia (Ischemic Colitis). Symptoms similar to irritable bowel syndrome can be caused by blockage of blood flow in the intestine. This is more likely to occur in elderly people.

Celiac Sprue. Celiac sprue, or celiac disease, is an intolerance to gluten (found in wheat) that triggers inflammation in the small intestine and causes diarrhea, vitamin deficiencies, and stool abnormalities. It occurs in some people with inflammatory bowel disease (IBD) and is usually first noticed in children.

Acute Appendicitis. Crohn's disease may cause tenderness in the right lower part of the abdomen, where the appendix is located, that resembles appendicitis.

Cancer. Colon or rectal cancers must always be ruled out when symptoms of IBD occur.