Several tests help your doctor find out where the swelling is in your gut, how serious it is, and rule out other conditions with similar symptoms. Blood tests check for anemia—too few red blood cells—as well as white blood cells and a protein called c-reactive protein, which rise when there is swelling or infection. Stool tests look for signs of inflammation and help rule out infections. A colonoscopy—a test that looks inside your large intestine with a small camera—is one of the most accurate tools doctors use. During the scope, the doctor may take a biopsy, a tiny tissue sample examined under a microscope. Imaging tests like CT scans and MRI create detailed pictures of your intestines. Ask your care team which tests are coming up and what each one is looking for.