During a colonoscopy, the doctor inserts a colonoscope into the rectum and through the large intestine to view images of the lining of the colon. The colonoscope also discharges air into the colon to make it expand for better visibility, according to WebMD. The doctor examines the images to see if there are any abnormalities in the colon.
A colonoscopy takes half an hour to an hour, states WebMD. Before the procedure starts, the doctor injects the patient with a tranquilizer. Although the patient must lie on his left side at the start of the procedure, sometimes the doctor asks him to shift his position when the colonoscope moves. The colonoscope is a long, pliable tube that measures about 1/2 inch in diameter.
Although the colonoscopy is mainly an observation procedure, if the doctor sees an abnormality, he might perform a biopsy. Tissue removed during the operation is analyzed afterwards. During the procedure, the doctor can also remove polyps, explains WebMD.
When the procedure is finished, the patient moves to a recovery room, where nurses observe him for about 30 minutes. If there are no complications after this, the patient leaves and resumes his normal diet. Rare complications of a colonoscopy are bleeding and puncture of the colon. Patients may need to stop taking blood-thinning medications for a few days after the procedure, reports WebMD.