Diagnosing inflammatory bowel disease (IBD) is a complex and lengthy process. The first step in diagnosing IBD is a visit to a physician for a medical history and physical examination. Patients may be asked about the duration of their symptoms, any family history of IBD and their cigarette smoking habits.  

Blood and stool samples may also be required. Blood tests can identify low red blood cell counts (anemia), high white blood cell counts (inflammation or infection) and nutrient levels. A stool sample analysis can rule out intestinal infections, which include symptoms similar to IBD symptoms.

There are many other diseases and infections that can include symptoms similar to IBD. Through a variety of diagnostic tests, a physician may also want to rule out evidence of:

• Sexually transmitted diseases (e.g., gonorrhea, chlamydia, herpes)
  
• Colorectal cancer
  
• Ischemic colitis (inflammation that occurs when not enough oxygen-rich blood flows to the bowel)
  
• Pelvic inflammatory disease
  
• Ectopic pregnancy (when an embryo implants outside the uterus)
  
• Ovarian cysts and tumors in women
  
• Celiac disease
  
• Tropical sprue

The two most common procedures used for diagnosing IBD are:

• Barium x-ray. Organs are coated with a chalky substance (barium) that shows up on x-rays. With upper GI barium tests, patients drink the barium for x-rays of the esophagus, stomach and/or small intestine. With lower GI barium tests, barium is administered through an enema for x-rays of the large intestine. These x-rays allow physicians to identify any abnormalities within the digestive tract.
  
  
• Colonoscopy. Examination using a small, flexible tube (with a light and camera) that is inserted into the anus and through the entire large intestine. This allows physicians to view the lining of the colon and identify the severity and extent of any disease. Patients are sedated during the procedure. A tissue sample may be taken for evaluation under a microscope (biopsy).

Additional diagnostic methods are sometimes used for patients with IBD. Computed axial tomography (CAT) scans are used to look for any sign of abdominal abscess that can result from IBD. An upper endoscopy may be used to identify abnormalities in the esophagus, stomach and first part of the small intestine. A new instrument, called a capsule endoscope, also allows physicians to look for abnormalities in the small intestine. Patients swallow a capsule that contains a tiny camera, which transmits images of the small intestine to a recorder for later viewing. This may be especially helpful for areas of the small intestine that are hard to reach during a conventional endoscopy, though the capsule should not be used in IBD patients with strictures because of concern regarding capsule passage.