Anal fistulas and colonoscopies cannot be done together; because anal fistulas themselves are caused by bacterial infections, and when a colonoscopy is done, it is even possible to bring bacteria into the intestines, causing inflammation of the rectum or colon. A colonoscopy is a screening method, and a painless colonoscopy can be performed under anesthesia. The colonoscopy is mainly used to check for diseases of the rectum and colon. The diseases examined are mainly intestinal inflammation, intestinal polyps, constipation of the large intestine, colon cancer, rectal cancer and other diseases. However, anal fistula is different. Anal fistula is a disease caused by perianal abscess, which cannot be solved by colonoscopy and must be treated surgically under anesthesia. This surgery involves cutting off the internal fistula and then removing all the necrotic tissues, which is an aseptic operation and can not be performed together with colonoscopy. Patients should go to the hospital for examination if they have any uncomfortable symptoms, and follow the doctor’s instructions to give the relevant diagnosis and treatment, to avoid causing delays in the condition.