Crohn's Disease - Exams and Tests

Exams and Tests

Crohn's disease is diagnosed through a medical history and physical exam, imaging tests to look at the intestines, and laboratory tests.

Crohn's disease can be difficult to diagnose. The disease may go undiagnosed for years because symptoms usually develop gradually and the same part of the intestine is not always involved. Other diseases can also have the same symptoms as Crohn's disease. But Crohn's disease tends to cause the intestine to have a cobblestone appearance, which can help doctors diagnose it. The pattern results from the repeated formation and healing of sores (ulcers) in the intestine.

The colon and rectum can be examined with flexible sigmoidoscopy or colonoscopy, in which a lighted viewing instrument is used to examine the inside of the colon. In general, colonoscopy is the preferred test because it can be used to examine the entire colon, while sigmoidoscopy reaches only the last 2 ft (0.6 m) of the colon. Both procedures can be used to take a sample (biopsy) of intestinal tissue. Imaging tests such as barium enema, computed tomography (CT) scan, and magnetic resonance imaging (MRI) may be helpful in locating abnormal openings (fistulas).

A stool analysis is often done, depending on symptoms, to look for blood, signs of bacterial infection, malabsorption, parasites, or the presence of white blood cells. This test can be used to distinguish Crohn's disease from irritable bowel syndrome (IBS), which is a less serious condition that sometimes has similar symptoms. White blood cells in stool indicate inflammation and possibly infection and are also a sign of Crohn's disease; their presence means you do not have IBS.

Stool analysis may be done during a flare-up if there is concern that new symptoms are caused by another problem. You can collect a stool sample, or the doctor may take a sample during sigmoidoscopy or colonoscopy.

Other exams and tests that may also be used to evaluate Crohn's disease include:

• Abdominal X-ray, which provides a picture of possible obstruction in the abdomen.
• Upper gastrointestinal (UGI) series with small-bowel follow-through to examine all of the small intestine. In this test the doctor examines the upper and part of the middle portions of the digestive tract. After you swallow a "shake" made of a white liquid (barium) and water, continuous X-rays (fluoroscopy) are taken to track the movement of the barium through the esophagus, stomach, and the small intestine. A video monitor displays the images.
• Upper gastrointestinal endoscopy, which allows your doctor to look at the interior lining of your esophagus, stomach, and duodenum with a thin, flexible imaging instrument called an endoscope.
• Barium enema, a test that allows the doctor to examine the large intestine (colon). For a barium enema, a white liquid (barium) is inserted through the rectum into the colon and large intestine. The barium outlines the inside of the colon so that it can be more clearly seen on an X-ray.
• Computed tomography (CT) scan, which uses X-rays to produce detailed pictures of structures inside the body.
• Magnetic resonance imaging (MRI), which uses a magnetic field and pulses of radio wave energy to provide pictures of organs and structures inside the body.
• Video capsule endoscopy (VCE), in which you swallow a tiny camera that records its trip through your digestive tract by sending images to a recording device that you wear on a belt. Your doctor later examines the images by downloading them from the recording device. The camera passes out of your body in stool within 10 to 48 hours. VCE is particularly useful in examining the small intestine, which is difficult to see with other endoscopic tests.
• Small bowel enteroscopy, which uses a longer, lighted flexible tube with a tiny camera that sends pictures of the small intestine to a video screen. This helps the doctor look at the small intestine. The doctor can also take small samples (biopsy) of the tissue.

Standard blood tests and urine tests may be used to check for anemia, inflammation, or malnutrition. Depending on the symptoms, an erythrocyte sedimentation rate (ESR, or sed rate) or C-reactive protein (CRP) blood test may be done to look for infection or inflammation. C-reactive protein is a substance produced by the liver as a result of inflammation in the body.

A biopsy of a sample of tissue from the lining of the intestine, collected during sigmoidoscopy or colonoscopy, can be used to confirm the diagnosis of Crohn's disease. A biopsy also may be done to find out whether a tumor is present. Multiple biopsies for cancer screening are often done in people who have had Crohn's disease of the colon or rectum for 8 to 10 years or more. Bowel biopsies are painless (other than the potential discomfort of the scope procedure) and remove only a tiny piece of tissue.

Early Detection

No screening test exists for Crohn's disease at this time. However, if you have had Crohn's disease affecting the colon or rectum for 8 to 10 years or longer, discuss with your doctor whether you need screening for colon cancer. Screening usually involves taking multiple-tissue biopsies during routine colonoscopy.