What causes ulcerative colitis?
The cause of ulcerative colitis is still unknown. Possible causes are thought to include viruses, bacteria, diet, stress, smoking and allergy. Current thinking is that it may be an autoimmune disease in which the body’s immune system attacks its own tissues. However, there are no proven theories yet.

What tests confirm a diagnosis of ulcerative colitis?
It may take time to confirm a diagnosis of ulcerative colitis as other bowel diseases may need to be excluded first. For example, rectal bleeding may be due to proctitis, but a more typical cause of rectal bleeding is hemorrhoids. If there has been blood loss a blood test can show anemia. The severity of inflammation present can also be shown by blood tests (a raised white cell count or erythrocyte sedimentation rate [ESR]). Stool specimens may be tested to exclude parasites or other causes of infection.

A endoscopy (sigmoidoscopy or colonoscopy) is usually required to confirm the diagnosis. In this procedure a fiber-optic tube connected to a video camera is passed into the rectum and up into the colon allowing the doctor to see the extent of the disease. Biopsies may also be taken during the endoscopy to confirm the severity of the inflammation. A biopsy involves a small sample of tissue being taken from the intestine for examination under a microscope. These tests can help the doctors decide which type of treatment is necessary. A barium enema may also be used. In this procedure a liquid is introduced into the rectum and colon via the anus allowing x-ray pictures of the intestine to be taken. This may show the presence of ulcerative colitis but is not as accurate in defining the severity or extent of the disease as an endoscopy or biopsy.