Skip to Main Content
Diagnosis Gastroenterology

Crohn's Disease

First your doctor will ask about your medical history and perform a physical evaluation. There is no single test that can provide a diagnosis of Crohn's disease, but rather a series of X-rays, laboratory tests, endoscopy and pathology tests that are used. These may include the following:

  • Blood Tests Blood tests may be done to check for anemia, which may indicate bleeding in the intestines. Blood tests also may uncover a high white blood cell count, which is a sign of inflammation somewhere in the body. C reactive protein, a marker of inflammation, also may be elevated.
  • Stool Sample By testing a stool sample, the doctor can tell if there is bleeding or infection in the intestines.
  • Small Bowel Radiograph Your doctor may perform a small bowel follow through to look at the small intestine. For this test, you will drink barium, a chalky solution that coats the lining of the small intestine, before X-rays are taken. The barium and irregularity of the border between the barium and intestine shows up white on X-ray film, revealing inflammation or other abnormalities in the intestine.
  • Colonoscopy: The term "colonoscopy" means looking inside the colon. The colon, or large bowel, is the last portion of your digestive tract. Its main function is to absorb water and store unabsorbed food products prior to their elimination. Colonoscopies are performed by a gastroenterologist, a doctor specially trained in digestive disorders. Your doctor will be assisted by specially trained nurses and technicians.

The procedure is performed using a colonscope. This device is a long, flexible tube that is about as thick as your index finger and has a small video camera and light on the end. By adjusting the various controls on the colonscope, the gastroenterologist can carefully examine the inside lining of the colon from the anus to the cecum and can enter the end of your small bowel, or terminal ileum, as well. The colonoscope contains a channel that allows instruments to be passed in order to take tissue or stool samples, remove polyps and provide other therapy.

The high quality picture from the colonoscope is shown on a television monitor. Colonoscopy provides the best imaging of the colon at present. It is a more precise examination than X-ray studies. This procedure also allows other instruments to be passed through the colonoscope. These may be used, for example, to painlessly remove a suspicious-looking growth or to take a biopsy, where a small piece of tissue is obtained, for further analysis. In this way, colonoscopy help doctors assess whether surgery is necessary as well as what type of surgery may be needed.

UCSF Health medical specialists have reviewed this information. It is for educational purposes only and is not intended to replace the advice of your doctor or other health care provider. We encourage you to discuss any questions or concerns you may have with your provider.