There is no definitive diagnostic test for Crohn’s disease. A doctor will diagnose Crohn’s disease based on medical history and physical examination, and the results of laboratory, endoscopic (appearance and biopsy results), and imaging tests.
- Blood tests are used for various purposes, including to determine the presence of anemia (low red blood cell count). 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.
Flexible Sigmoidoscopy and Colonoscopy. Flexible sigmoidoscopy and colonoscopy are procedures that involve snaking a fiberoptic tube called an endoscope through the rectum to view the lining of the colon. The doctor can also insert instruments through it to remove tissue samples.
- Sigmoidoscopy, which is used to examine only 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.
- Colonoscopy allows a view of the entire colon and requires a sedative, but it is still a painless procedure performed on an outpatient basis. A colonoscopy can also help screen for colon cancer.
These procedures can help a doctor to distinguish between ulcerative colitis and Crohn's disease, as well as other diseases.
Wireless Capsule Endoscopy. Wireless capsule endoscopy (WCE) is a newer imaging approach that is sometimes used for diagnosing Crohn's disease. With WCE, the patient swallows a capsule containing a tiny camera that records and transmits images as it passes through the gastrointestinal tract.
Upper and Lower Gastrointestinal Barium X-Rays. An upper gastrointestinal barium x-ray may be used if Crohn's disease is suspected in the small intestine. Swallowed barium passes into the small intestine and shows up on an x-ray image, which may reveal inflammation, ulcers, and other abnormalities.
Review Date: 09/28/2010
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.