Diagnosis

Your doctor will likely diagnose inflammatory bowel disease only after ruling out other possible causes for your signs and symptoms. To help confirm a diagnosis of IBD, you will need a combination of tests and procedures:

Lab tests

• Tests for anemia or infection. 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 from bacteria or viruses.
• Stool studies. You may need to provide a stool sample so that your doctor can test for hidden (occult) blood or organisms, such as parasites, in your stool.

Endoscopic procedures

• Colonoscopy. This exam allows your doctor to view your entire colon using a thin, flexible, lighted tube with a camera at the end. During the procedure, your doctor can also take small samples of tissue (biopsy) for laboratory analysis. A biopsy is the way to make the diagnosis of IBD versus other forms of inflammation.
• 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.
• Upper endoscopy. In this procedure, your doctor uses a slender, flexible, lighted tube to examine the esophagus, stomach and first part of the small intestine (duodenum). While it is rare for these areas to be involved with Crohn's disease, this test may be recommended if you are having nausea and vomiting, difficulty eating, or upper abdominal pain.
• Capsule endoscopy. This test is sometimes used to help diagnose Crohn's disease involving your small intestine. You swallow a capsule that has a camera in it. The images are transmitted to a recorder you wear on your belt, after which the capsule exits your body painlessly in your stool. You may still need an endoscopy with a biopsy to confirm a diagnosis of Crohn's disease. Capsule endoscopy should not be performed if there is a bowel obstruction.
• Balloon-assisted enteroscopy. For this test, a scope is used in conjunction with a device called an overtube. This enables the doctor to look further into the small bowel where standard endoscopes don't reach. This technique is useful when a capsule endoscopy shows abnormalities, but the diagnosis is still in question.

Imaging procedures

• 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.
• Computerized tomography (CT) scan. You may have a CT scan — a special X-ray technique that provides more detail than a standard X-ray does. This test looks at the entire bowel as well as at tissues outside the bowel. CT enterography is a special CT scan that provides better images of the small bowel. This test has replaced barium X-rays in many medical centers.
• Magnetic resonance imaging (MRI). An MRI scanner uses a magnetic field and radio waves to create detailed images of organs and tissues. An MRI is particularly useful for evaluating a fistula around the anal area (pelvic MRI) or the small intestine (MR enterography). Unlike CT, there is no radiation exposure with MRI.