Crohn's Disease

Diagnosis

Historically, Crohn's disease has been difficult to diagnose. In part, this is because its symptoms are similar to those of other bowel disorders, including ulcerative colitis and irritable bowel syndrome. A larger problem is that the small intestine has been difficult to examine using traditional methods.

Mayo Clinic has been instrumental in developing advanced imaging techniques that make it possible for doctors to thoroughly inspect the small bowel and was one of the first major medical institutions to use them.

Your doctor may order other tests, including simple laboratory tests and traditional endoscopy procedures. Over time, you may also need tests to monitor the disease and to watch for complications and side effects of medications.

Laboratory Tests

If you have symptoms of Crohn's disease, you're likely to begin by having one or more noninvasive laboratory tests, including blood tests to check for anemia and infection, liver function tests to screen for liver and bile duct problems, and stool studies to rule out bacterial, viral and parasitic infections.

Endoscopy

The next step in diagnosis at Mayo Clinic is usually a visual examination of the colon itself using an endoscope, a thin, flexible tube with a lighted camera inside its tip. The camera sends magnified images of the colon lining to a television screen. A sigmoidoscopy is an endoscopic examination of the lower third of your large intestine — the sigmoid colon. A colonoscopy is a more complete test that looks at your entire colon, sometimes including the very end of the small intestine (ileum). During endoscopic procedures, your surgeon usually removes one or more small tissue samples (biopsies) and sends them to a pathologist for further study.

In some cases, you may also have an endoscopic ultrasound (EUS), which uses an ultrasound probe attached to an endoscope to view problems deep within the intestine. EUS can diagnose fistulas — abnormal tunnels that develop between loops of intestine or between the intestine and other organs — and provides precise information about the location and size of unexplained bleeding. Mayo doctors have offered EUS for more than two decades and are among the most experienced in the world in endoscopic ultrasound techniques.

Mayo Clinic physicians have also been leaders in studying and using capsule endoscopy, another noninvasive procedure for evaluating the small intestine. The test is performed using a capsule endoscope, a device about the size of a large pill. The endoscope is composed of a strong light source, tiny camera and transmitter. Once swallowed, the endoscope travels through your digestive tract, taking thousands of pictures and transmitting them to a recorder that you wear around your waist.

Because capsule endoscopy views the entire 30-foot length of the small intestine, it can help find problems beyond the reach of traditional endoscopic procedures. In addition, the clarity of its images allows doctors to detect problems missed by other diagnostic methods. Read more on capsule endoscopy.

If you have unexplained bleeding that can't be found by other methods, your doctor may perform a double balloon enteroscopy, a procedure that uses a scope equipped with two balloons to look at most of the small intestine. The balloons inflate inside the digestive tract, allowing a clear view inside folds of tissue.

Radiology Tests

CT and MR enterography are novel, noninvasive imaging techniques that allow doctors to see intestinal inflammation, abscesses and fistulas in the small bowel. Doctors in Mayo's Inflammatory Bowel Disease Clinics now routinely use both imaging techniques. Noninvasive imaging has proven far more effective than traditional barium studies in detecting Crohn's disease and its complications. It also helps your physician make treatment decisions and decide when surgery may be needed.

• Multiphase CT enterography: Multiphase CT enterography uses very fast CT scanning and a contrast dye to obtain detailed cross-sectional images of the abdomen. Mayo Clinic radiologists were instrumental in developing this procedure and have done more than 3,000 CT enterographies. Unlike a conventional CT scan, CT enterography provides an exceptional view of the small intestine. Read more on multiphase CT enterography.
• MR enterography (MRE): MRE uses a magnetic field and radio waves rather than radiation to create high contrast images of the small intestine as well as to locate problems outside the bowel. MRE spares patients exposure to ionizing radiation found in X-rays and CT scans. It's especially important for tracking the progress of Crohn's disease in younger patients, who may otherwise be exposed to undue amounts of radiation over a lifetime.