Please note: This information was current at the time of publication. But medical information is always changing, and some information given here may be out of date. For regularly updated information on a variety of health topics, please visit, the AAFP patient education Web site.

Information from Your Family Doctor

What You Should Know About Flexible Sigmoidoscopy


Am Fam Physician. 1999 Jan 15;59(2):327-358.

See related article on flexible sigmoidoscopy.

What is flexible sigmoidoscopy?

In this exam, your doctor uses an instrument called a “flexible sigmoidoscope” (say: sig-moydo-scope) to look for problems in your rectum and lower colon. The rectum and lower colon are parts of the large intestine, or bowel.

The sigmoidoscope is a long, thin tube with a tiny camera on the end. The tube is put into the anus (the opening to the bowel) and moved slowly into the colon. A light at the tip of the scope lets your doctor see the walls of the bowel. Your doctor will look for changes on the bowel wall that may be caused by a disease, a cancer or a condition that might turn into cancer. Your doctor can also use this tube to look for the cause of bleeding or pain.

Why should I have this exam?

Everyone over 50 years of age should be checked for colorectal cancer each year. You might be checked with a stool test. A tiny bit of stool (bowel movement) is put on a special kind of paper. It turns colors if blood is in the stool. Or your doctor might check you with flexible sigmoidoscopy. Flexible sigmoidoscopy can help your doctor find cancer or precancer early enough to cure. If you have a family history of colon problems or if you have pain in your belly or rectal bleeding, your doctor may want you to have flexible sigmoidoscopy.

How do I get ready for this exam?

Before the exam, you need to empty your lower colon and rectum of stool. Your doctor will tell you how to clean out your bowel with enemas and liquid medicines. During this time, you can probably keep taking your regular medicines, but you need to tell your doctor if you’re taking aspirin every day, or a blood thinner, or if you’re allergic to any medicines.

What can I expect during flexible sigmoidoscopy?

The exam usually lasts 5 to 15 minutes. During that time you may feel pain from cramps in your belly. You may feel like you have to go to the bathroom. Your doctor may need to take a small tissue sample (called a biopsy specimen) from the wall of your bowel. This won’t hurt.

What happens after the exam?

You should be able to return to your normal activities right after you leave your doctor’s office. If a biopsy sample was taken, you may see a small amount of blood in your next stool. If you feel bloated or have cramps, you’ll probably feel better after you pass gas.

Right after the exam, your doctor will be able to tell you what was seen through the scope. It may be several days before you find out what the biopsy sample showed. The biopsy sample has to be sent to a lab. Your doctor will call you or ask you to come back to the office to find out what the biopsy showed.

If you get a fever or have a pain in your belly that gets worse after the exam, you should call your doctor right away. These might be signs of infection.

What can I do so I don’t get colorectal cancer?

You can lower your risk of getting colorectal cancer by taking good care of yourself. The American Cancer Society recommends that you do these things:

  • Exercise for 30 minutes every day.

  • Eat a lot of high-fiber, low-fat foods, such as cereal and bran.

  • Stop smoking, if you smoke.

  • Limit alcohol intake.


This handout is provided to you by your family doctor and the American Academy of Family Physicians. Other health-related information is available from the AAFP online at

This information provides a general overview and may not apply to everyone. Talk to your family doctor to find out if this information applies to you and to get more information on this subject.

Copyright © 1999 by the American Academy of Family Physicians.
This content is owned by the AAFP. A person viewing it online may make one printout of the material and may use that printout only for his or her personal, non-commercial reference. This material may not otherwise be downloaded, copied, printed, stored, transmitted or reproduced in any medium, whether now known or later invented, except as authorized in writing by the AAFP. Contact for copyright questions and/or permission requests.

Want to use this article elsewhere? Get Permissions

CME Quiz

Email Alerts

Don't miss a single issue. Sign up for the free AFP email table of contents.

Sign Up Now

Navigate this Article