Tests For Crohn’s Disease

Written by Michael Kerr | Published on September 2, 2014
Medically Reviewed by Brenda B. Spriggs, MD, MPH, MBA on September 2, 2014

Find out which tests doctors may use to diagnose Crohn's disease and rule out other conditions.

What Is Crohn’s Disease?

Crohn’s disease is a condition that can affect the entire digestive system, including the colon, small intestine, or large intestine. Often, the end of the small intestine (the ileum) is characteristically affected. It’s characterized by stomach pain, diarrhea, or other serious digestive symptoms brought on by inflammation.

Crohn’s disease is a serious condition. Left untreated, it could cause intestinal scarring (stenosis), fistulas, obstruction in the bowels, ulcers or colon cancer. In serious cases, Crohn’s disease can be life threatening. There is no known cause or cure for Crohn’s disease. With treatment, you can expect to live a normal life.

Common symptoms of Crohn’s disease include:

  • diarrhea
  • stomach pains
  • cramping
  • bloody stool
  • ulcers
  • weight loss
  • loss of appetite
  • malnutrition
  • fever
  • fatigue

How to Test For Crohn’s Disease

To diagnose Crohn’s disease, your doctor will first do a full examination to rule out other conditions. There’s no simple way to diagnose Crohn’s, so your doctor must first determine what is causing your symptoms. Because of this, it can take a long time to finally get a diagnosis of Crohn’s disease. There are a number of tests that can be used to diagnose this condition.

The primary tests for Crohn’s disease include imaging tests. Your doctor will need to be able to see what’s going on with your digestive tract to make the diagnosis. Some tests show imaging from the outside, like x-rays, and others involve examining the bowel with an endoscope for direct visualization and using a camera, during the procedure, to document any abnormalities. Often a biopsy of the tissues is also performed. Since Crohn’s disease can affect various places in the digestive tract and most tests have specific coverage areas, more than one type of test is usually needed.

Blood Test

Blood tests can be used to look for infection or antibodies in the blood. Having antibodies doesn’t mean you have Crohn’s. Blood tests can show an increased level of white blood cells or platelets in the blood. An increase in these levels could mean inflammation in the body. Inflammation could mean Crohn’s or other inflammatory diseases. Blood tests would never be used as the only test for Crohn’s. Other tests and a biopsy would probably be needed.

Stool Tests

Stool tests can be used to look for blood. Blood in the stool is a sign of a digestive condition, like Crohn’s. To do a stool test, you will need to provide a sample to your doctor. The sample will be sent to a lab for testing. They will look for signs of blood or other abnormalities. This test may be awkward, but it shouldn’t be painful or have any side effects.

Imaging Tests

Imaging tests include X-ray, magnetic resonance imaging (MRI) or computerized tomography (CT) scan. These images are used to see the digestive tract from the outside. They help your doctor see the tissues and document any damage or inflammation. Often focused on the small intestine, imaging tests could also include the stomach or colon. Sometimes your doctor will have you drink a solution called barium that causes contrast on the pictures. This allows your doctor to see variation in tissues beyond the coverage area of other tests.  One specific test, called the upper GI series, includes a variety of imaging tests designed to get a complete picture of the small intestine. The CT scans or MRI show more tissues that other tests don’t reveal. This helps pinpoint the location of the inflammation. This test also helps diagnose potentially serious complications from the disease, like fistulas or abscesses.


Biopsy includes taking a small tissue sample for testing. Often the sample is collected during another test, like a colonoscopy. The sample is then sent to a lab for testing of the tissues. The lab will look for signs of inflammation or other problems with the tissues. Biopsies help confirm what was seen during an endoscopy or imaging tests.


Endoscopy is a test where a thin, flexible tube is inserted through the anus to look at the inner walls of the colon. Colonoscopy and sigmoidoscopy are types of endoscopy. With endoscopy, a sample can be collected for further testing. Sometimes people have small groupings of cells (granulomas) in the colon that can only be seen with a colonoscopy. Granulomas usually point to Crohn’s. The downside of colonoscopy is that it’s an uncomfortable and invasive procedure. The benefit is that its one of the few tests that allow doctors to see the inside of the colon. With this procedure, they can even visualize the space between the small intestine and colon where damage from Crohn’s disease is often seen. Your doctor can view the entire colon with a colonoscopy. Sigmoidoscopy is similar to a colonoscopy, but, with this procedure, your doctor can only examine at the end (distal)  part of the colon.

Capsule Endoscopy

Capsule endoscopy is a revolutionary test used when other tests aren’t conclusive. For a capsule endoscopy, you need to swallow a small capsule that has a tiny camera inside. This allows for images of the inside of your digestive tract. If the images come back to show some signs of Crohn’s, your doctor may do more testing. The benefit of a capsule endoscopy is that it’s minimally invasive. The capsule is designed to pass through your digestive tract without causing discomfort and provide useful imaging to help diagnose Crohn’s disease or other digestive tract issues. The downside is that it doesn’t take biopsies and only sees into the small intestine. A colonoscopy is still usually done to see the colon.

Treating Crohn’s Disease

There are currently no known cures for Crohn’s disease. Some treatment options may help reduce the risk of symptom flare-up. The goal of treatment options is to minimize symptoms, prevent complications, and reduce inflammation.

Medications, like anti-inflammatory drugs, immunosuppressive medications, or antibiotics are the primary options for treating Crohn’s disease. Other treatment options include:

  • laxatives
  • anti-diarrheal medications
  • pain relievers
  • iron supplements
  • nutritional therapy or dietary changes
  • vitamin B-12 injections
  • calcium supplements
  • vitamin D supplements

Reducing stress and keeping your immune system healthy may also help with symptoms.

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Show Sources

  • Crohn's disease: MedlinePlus Medical Encyclopedia. (2010, December 13). National Library of Medicine - National Institutes of Health. Retrieved January 26, 2012, from http://www.nlm.nih.gov/medlineplus/ency/article/000249.htm
  • Crohn's Disease - National Digestive Diseases Information Clearinghouse. (n.d.). Home - National Digestive Diseases Information Clearinghouse. Retrieved January 28, 2012, from http://digestive.niddk.nih.gov/ddiseases/pubs/crohns/
  • Saibil, F. G. (2011). Crohn's disease and ulcerative colitis: everything you need to know : the complete practical guide (3rd ed.). Richmond Hill, Ont.: Firefly Books.
  • Warner, A. S., & Barto, A. E. (2010). 100 questions & answers about Crohn's disease and ulcerative colitis: a Lahey Clinic guide (2nd ed.). Sudbury, Mass.: Jones and Bartlett Publishers.

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