Crohn's disease is diagnosed using a combination of methods since there is no single test for it. Typical tests include:

• Blood tests: To check for anemia, infection, and inflammation markers such as C-reactive protein and white blood cell counts.
• Stool tests: To detect infections or inflammation markers like calprotectin.
• Endoscopy: This includes colonoscopy, enteroscopy, and upper GI endoscopy, where a camera on a flexible tube examines the digestive tract visually. Biopsies (small tissue samples) may be taken to confirm inflammation and other signs of Crohn's disease.
• Imaging tests: CT scans, MRI, and specialized forms like CT enterography and MR enterography visualize inflammation and complications in the intestines.
• Capsule endoscopy: Swallowing a camera capsule allows visualization of the small intestine, especially helpful when disease is suspected there but not seen via other endoscopies.

Doctors first gather medical history, perform a physical exam, and then use these tests to confirm Crohn's disease, determine its severity and location, and exclude other causes of symptoms.