Crohn's Disease

Diagnosis

The diagnosis of Crohn's disease is based on a combination of exams: endoscopic, X-rays and histologic blood and tissue tests. Upon diagnosis, patients may need additional tests to monitor the disease and diagnose possible complications or side effects of medications.

Laboratory Tests

CBC (complete blood count) tests detect high white blood cell counts, which could indicate intestinal inflammation or infection and low blood counts (anemia) which might reveal intestinal bleeding. The presence of C-reactive protein can also indicate intestinal inflammation. Tests also monitor for side effects of certain medications. Liver function tests help screen for liver and bile duct abnormalities. Stool studies determine whether patients have treatable bacterial infections. Antibody tests can help clarify the situation for "indeterminate colitis" patients without a definite diagnosis.

Endoscopy

Several types of endoscopes are used to determine if the patient has ulcerative colitis or Crohn's disease and how much bowel is affected. All use a thin, flexible tube with a lighted camera inside the tip, which allows doctors to look at the lining of the gastrointestinal (GI) tract. The image is magnified and appears on a television screen. Each procedure is named according to the section of GI tract examined:

• Sigmoidoscopy — Examines the lining of the lower third of the large intestine (the sigmoid colon).
• Colonoscopy — Examines the lining of the entire large intestine (colon), and sometimes can peek into the very end of the small intestine (or ileum).
• ERCP (Endoscopic retrograde cholangiopancreatography) — Examines the bile ducts in the liver and the pancreatic duct.
• Endoscopic ultrasound — Uses an ultrasound probe attached to an endoscope to obtain deep images of the gut below the surface. Used to diagnose perianal fistulas in patients with Crohn's disease.
• Capsule endoscopy — Patients swallow a vitamin-sized capsule with a camera inside to produce images of sections of the small intestine that are beyond the reach of an EGD. Read more on capsule endoscopy.

Radiology Tests

These radiologic tests provide information that endoscopy alone cannot:

Plain X-rays
Plain X-rays without contrast detect blockage in the large intestine.

X-rays with Contrast
Contrast X-rays are used with endoscopy in monitoring and treating Crohn's. These X-rays track special liquid contrast, usually barium, as it passes through the intestine, highlighting specific conditions.

CT Scan
A CT scan takes simultaneous X-rays from different angles to reconstruct images of the internal organs.

Multiphase CT enterography
Multiphase CT enterography (MCTE) is a new noninvasive procedure that uses very fast CT scanning combined with liquid intake to obtain detailed cross-sectional images of the abdomen. Mayo Clinic has been a leader in the development of this procedure and has found it to be very valuable in identifying inflammation in patients with Crohn's disease.