How is Crohn's disease diagnosed?

A number of tests are used to diagnose Crohn's disease. First, your doctor will review your medical history. This information is helpful because Crohn's disease is more common in people who have a first-degree relative with IBD. After the physical examination is complete, the doctor may order the following tests:

  • Endoscopy (such as colonoscopy or sigmoidoscopy): A flexible, lighted tube (called an endoscope) is inserted into the rectum to view the inside of the rectum and colon. (Colonoscopy shows a greater portion of the colon than sigmoidoscopy.) A small sample of tissue may also be taken for testing (biopsy).
  • Blood tests: The doctor will look for signs of anemia, or a high white blood cell count, which will mean that there is inflammation or an infection somewhere in the body.
  • Barium X-ray (barium enema or small bowel series): X-rays are taken of either the upper or lower intestine. Barium coats the lining of the small intestine and colon, and shows up as white on an X-ray, which allows the doctor to see any abnormalities.
  • CT scan: X-ray of the abdomen that shows how widespread the inflammation is, and how severe it is. It also identifies lesions in other organs.