A colonoscopy is a diagnostic test that allows a physician to examine the inner lining of the rectum and colon for bleeding, polyps, tumors or areas of inflammation, according to WebMD. The test is commonly performed on patients experiencing gastrointestinal symptoms, such as pain or intestinal bleeding, reports Cleveland Clinic.
Doctors recommend a screening colonoscopy for all patients over age 50 and younger patients with a family history of colorectal cancer, according to Cleveland Clinic. The colon must be cleaned out before a colonoscopy is performed. Patients prepare for the procedure by drinking a bowel prep solution one to two days before the test.