During a colonoscopy, a colonoscope (a long, flexible, lighted tube) is inserted into the rectum. Attached to the device is a small video camera that takes images or videos of the large intestine.

The internal lining of the colon is inspected for polyps, ulcers or other abnormalities. If polyps exist, they may be removed during the same procedure via a polypectomy. In addition to detecting cancer, a colonoscopy helps doctors evaluate the potential cause of certain symptoms, such as abdominal pain, rectal bleeding, constipation, diarrhea or a change in bowel habits. If a lesion is found, a colonoscopy may be used to perform a biopsy, which involves collecting samples of tissues or cells for further analysis.

To improve the accuracy of colonoscopy procedure results, the colon must be as clear as possible. Patients are given detailed instructions on how to prepare for the procedure by drinking cleansing solution and following a clear-liquid diet for a day.

A colonoscopy itself typically takes 15 to 60 minutes, though patients should expect to remain onsite for two to three hours, to make time for preparation and recovery. Patients are sedated during the procedure to help them relax and tolerate discomfort. They may experience pressure, bloating or cramping after the procedure. Results are usually explained by a patient’s doctor, and, if applicable, biopsy samples are sent to a pathologist for testing.