Diagnosis for Crohn's Disease
A number of tests are used to distinguish Crohn's disease from other gastrointestinal conditions. 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 -- mother, father, sister, or brother -- with IBD. After a physical examination is done, the doctor may order the following tests:

Blood tests: When testing the blood, the doctor will look for signs of anemia or a high white blood cell count that could indicate inflammation or infection somewhere in the body.

Barium X-ray (barium enema or small bowel series): X-rays are often taken of either the upper or lower intestine. Barium coats the lining of the small intestine and colon and shows up white on an X-ray. This characteristic enables doctors to view any abnormalities.

Endoscopy (such as colonoscopy or sigmoidoscopy): During this procedure, a flexible, lighted tube called an endoscope is inserted into the rectum and used to view the inside of the rectum and colon. A colonoscopy shows a greater portion of the colon than a sigmoidoscopy does. A small sample of tissue may be taken for testing -- biopsy.