Diagnosing inflammatory bowel disease is a complex procedure involving an array of different tests. Read about eight different signs and symptoms of IBD here. Here are some types of tests that may be needed to diagnosed IBD: Complete blood count and white blood cell counts are used for diagnosing IBD. In addition, the detection of C-reactive protein in blood and the evaluation of the erythrocyte sedimentation rate can help to determine the rates of inflammation and infection in the patient. Learn more about ulcerative colitis from a patient’s point of view.