During a colonoscopy, you'll wear a gown but likely nothing else. Sedation is usually recommended. Sometimes a mild sedative is given in pill form. In other cases, the sedative is combined with an intravenous pain medication to minimize any discomfort.
You'll begin the exam lying on your side on the exam table, usually with your knees drawn toward your chest. The doctor will insert a colonoscope into your rectum. The scope — which is long enough to reach the entire length of your colon — contains a light and a tube (channel) that allows the doctor to pump air into your colon. The air inflates the colon, which provides a better view of the lining of the colon. When the scope is moved or air is introduced, you may feel abdominal cramping or the urge to have a bowel movement.
The colonoscope also contains a tiny video camera at its tip. The camera sends images to an external monitor so the doctor can study the inside of your colon. The doctor can also insert instruments through the channel to take tissue samples (biopsies) or remove polyps or other areas of abnormal tissue.
A colonoscopy typically takes about 20 minutes to an hour.
After the exam
After the exam, it takes about an hour to begin to recover from the sedative. You'll need someone to take you home because it can take up to a day for the full effects of the sedative to wear off. Don't drive or go back to work for the rest of the day.
If your doctor removed a polyp during your colonoscopy, you may be advised to eat a special diet temporarily.
You may feel bloated or pass gas for a few hours after the exam, as you clear the air from your colon. Walking may help relieve any discomfort.
You may also notice a small amount of blood with your first bowel movement after the exam. Usually this isn't cause for alarm. Consult your doctor if you continue to pass blood or blood clots or if you have persistent abdominal pain or a fever of 100 F (37.8 C) or higher.
Jun. 11, 2014
A colonoscopic examination involves gently inserting a fiber-optic colonoscope into your rectum and large intestine to view your lower gastrointestinal tract. This video shows a polyp being removed from the wall of the colon.
- Pope JB. Pfenninger and Fowler's Procedures for Primary Care. 3rd ed. Philadelphia, Pa.: Mosby Elsevier; 2011. http://www.clinicalkey.com. Accessed March 5, 2014.
- Lee L, et al. Overview of colonoscopy in adults. http://www.uptodate.com/home. Accessed March 6, 2014.
- Colonoscopy. National Digestive Diseases Information Clearinghouse. http://digestive.niddk.nih.gov/ddiseases/pubs/colonoscopy/index.aspx. Accessed March 4, 2014.
- Colorectal cancer screening. Bloomington, Minn.: Institute for Clinical Systems Improvement. https://www.icsi.org/guidelines__more/catalog_guidelines_and_more/catalog_guidelines/catalog_prevention__screening_guidelines/colorectal/. Accessed March 6, 2014.
- Levin B, et al. Screening and surveillance for the early detection of colorectal cancer and adenomatous polyps, 2008: A joint guideline from the American Cancer Society, the US Multi-Society Task Force on Colorectal Cancer, and the American College of Radiology. Gastroenterology. 2008;134:1570.
- Picco MF (expert opinion). Mayo Clinic, Jacksonville, Fla. March 19, 2014.
- Lieberman DA, et al. Guidelines for colonoscopy surveillance after screening and polypectomy: A consensus update by the US Multi-Society Task Force on Colorectal Cancer. Gastroenterology. 2012;143:844.
- AskMayoExpert. Screening recommendations for average-risk, asymptomatic women. Rochester, Minn.: Mayo Foundation for Medical Education and Research; 2013.
- AskMayoExpert. Screening recommendations for average-risk, asymptomatic men. Rochester, Minn.: Mayo Foundation for Medical Education and Research; 2013.
- A-Rahim YI, et al. Bowel preparation for colonoscopy and flexible sigmoidoscopy in adults. http://www.uptodate.com/home. Accessed March 28, 2014.