Your doctor will likely diagnose ulcerative colitis after ruling out other possible causes for your signs and symptoms. 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 — a condition in which there aren't enough red blood cells to carry adequate oxygen to your tissues — or to check for signs of infection.
- Stool sample. White blood cells in your stool can indicate ulcerative colitis. A stool sample can also help rule out other disorders, such as infections caused by bacteria, viruses and parasites.
- 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. Your doctor uses a slender, flexible, lighted tube to examine the rectum and sigmoid, the last portion of your colon. If your colon is severely inflamed, your doctor may perform this test instead of a full colonoscopy.
- X-ray. If you have severe symptoms, your doctor may use a standard X-ray of your abdominal area to rule out serious complications, such as a perforated colon.
- CT scan. A CT scan of your abdomen or pelvis may be performed if your doctor suspects a complication from ulcerative colitis. A CT scan may also reveal how much of the colon is inflamed.
- Computerized tomography (CT) enterography and magnetic resonance (MR) enterography. Your doctor may recommend one of these noninvasive tests if he or she wants to exclude any inflammation in the small intestine. These tests are more sensitive for finding inflammation in the bowel than are conventional imaging tests. MR enterography is a radiation-free alternative.