Please note: This information was current at the time of publication but now may be out of date. This handout provides a general overview and may not apply to everyone. 

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

See related article on flexible sigmoidoscopy.

What is flexible sigmoidoscopy?

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

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

Why should I have this exam?

Everyone over 50 years of age should bechecked for colorectal cancer each year. Youmight be checked with a stool test. A tiny bit ofstool (bowel movement) is put on a specialkind of paper. It turns colors if blood is in thestool. Or your doctor might check you withflexible sigmoidoscopy. Flexible sigmoidoscopycan help your doctor find cancer or precancerearly enough to cure. If you have a familyhistory of colon problems or if you have pain inyour belly or rectal bleeding, your doctor maywant you to have flexible sigmoidoscopy.

How do I get ready for this exam?

Before the exam, you need to empty yourlower colon and rectum of stool. Your doctorwill tell you how to clean out your bowel withenemas and liquid medicines. During this time,you can probably keep taking your regularmedicines, but you need to tell your doctor ifyou’re taking aspirin every day, or a bloodthinner, or if you’re allergic to any medicines.

What can I expect during flexiblesigmoidoscopy?

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

What happens after the exam?

You should be able to return to your normalactivities right after you leave your doctor’soffice. If a biopsy sample was taken, you maysee a small amount of blood in your next stool.If you feel bloated or have cramps, you’llprobably feel better after you pass gas.

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

If you get a fever or have a pain in your bellythat gets worse after the exam, you should callyour doctor right away. These might be signs ofinfection.

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. TheAmerican 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.

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