by Editorial Staff and Contributors
Click here to view an animated version of this procedure.
A colonoscopy is an exam of the large intestine, also known as the colon. The exam is done with a tool called a colonoscope. The colonoscope is a flexible tube with a tiny camera on the end. This tool allows the doctor to view the inside of your colon.
Reasons for Procedure TOP
A colonoscopy is used to examine, diagnose, and treat problems in your colon. The procedure is most often done to:
Possible Complications TOP
Complications are rare, but no procedure is completely free of risk. If you are planning to have a colonoscopy, your doctor will review a list of possible complications, which may include:
Factors that may increase the risk of complications include:
Be sure to discuss these risks with your doctor before the procedure.
What to Expect TOP
Prior to Procedure
Your doctor will likely do the following:
Talk to your doctor about your medications. You may be asked to stop taking some medications up to one week before the procedure.
On the day of the procedure:
Emptying the Colon
Your colon must be completely clean before the procedure. Any stool left in the colon will block the view. This preparation may start several days before the procedure. Follow your doctor's instructions, which may include any of the following cleansing methods:
For the entire day before your procedure:
Your doctor may give you medication to help you relax. You'll probably feel sleepy.
Description of the Procedure TOP
You will lie on your left side. Your knees will be drawn up toward your chest. The colonoscope will be slowly inserted through the rectum. The colonoscope will inject air into the colon. The doctor will be able to see the lining of the colon with a small video camera on the colonoscope. The colonoscope will be gently passed through the colon to view the entire area.
A tissue sample or polyps may be removed during the procedure. This is done with small tools passed through the colonoscope.
How Long Will It Take? TOP
Less than one hour
Will It Hurt? TOP
Most people report some discomfort when the instrument is inserted. You may also feel some cramping or lower abdominal pain during the procedure. Medication will help decrease discomfort, some will sleep through the procedure.
After the procedure, gas pains and cramping are common. These pains should go away with the passing of gas.
Post-procedure Care TOP
If any tissue was removed:
Be sure to follow your doctor's instructions when you return home.
Call Your Doctor TOP
After arriving home, contact your doctor if any of the following occur:
If you think you have an emergency, call for emergency medical services right away.
American Society for Gastrointestinal Endoscopy
National Institute of Diabetes and Digestive and Kidney Diseases
Canadian Association of Radiologists
Public Health Agency of Canada
Colonoscopy. National Institute of Diabetes and Digestive and Kidney Diseases website. Available at:
...(Click grey area to select URL)
Updated September 11, 2013. Accessed September 15, 2014.
Frequently asked questions about colonoscopy and Sigmoidoscopy. American Cancer Society website. Available at:
...(Click grey area to select URL)
Accessed September 15, 2014.
6/2/2011 DynaMed's Systematic Literature Surveillance http://www.dynamed...: Mills E, Eyawo O, Lockhart I, Kelly S, Wu P, Ebbert JO. Smoking cessation reduces postoperative complications: a systematic review and meta-analysis. Am J Med. 2011;124(2):144-154.
Last reviewed September 2016 by Daus Mahnke, MD
Last Updated: 8/9/2017
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