1. Health
You can opt-out at any time. Please refer to our privacy policy for contact information.

Discuss in my forum

What is a Flexible Sigmoidoscopy?

Learn About Flexible Sigmoidoscopy, So You Know What to Expect With This Test


Updated June 24, 2014

Understanding Flexible Sigmoidoscopy

Flexible sigmoidoscopy is one of the more common tests that can be used to screen for colon cancer.

What is a Flexible Sigmoidoscopy?

A flexible sigmoidoscopy is a test that doctors use to look for and remove adenomas and polyps, growths in the colon that if left untreated, may turn into colon cancer. This test is also used to screen for colon cancer itself.

How Do You Prepare for a Flexible Sigmoidoscopy?

To prepare for this test, your doctor or nurse will give you instructions for the day or two before. This will involve taking laxatives or other medications and possibly following a special diet. This clears the stool out of your colon so your doctor can see everything clearly during the test.

How Not to Dread Colon Cancer Screening provides detailed information on how to get ready for this test, along with tips for making this preparation easier.

What Happens During the Flexible Sigmoidoscopy Test?

During a sigmoidoscopy, your doctor inserts a thin tube into your rectum and into the first two feet—or about half—of your colon. Air will be put into your colon, as well, to allow for a better view. This may cause discomfort, but it should not hurt. If it does hurt, don’t suffer in silence; tell your doctor.

Will I Be Sedated During Flexible Sigmoidoscopy?

You can choose to be sedated or "knocked out" during the procedure, but you’ll need a ride home if you go this route. Many people complete a sigmoidoscopy test, which takes about 10-20 minutes, without any type of sedative. Discuss with your doctor what’s best for you.

What Happens After My Flexible Sigmoidoscopy?

If your doctor finds any suspicious growths, often referred to as polyps or adenomas, he or she will remove them at that time. This colon tissue sample will be sent to a lab to check for cancer.

What are the Possible Complications of Flexible Sigmoidoscopy?

A possible complication of this test is puncture of the colon, but thankfully, this is very rare.

You may have some gas pains as the air from the test leaves your colon. You may also see a small amount blood in your stool for a day or two after the test, but this is usually not serious. If in doubt, call your doctor.

Another possible problem with this test is something called a false negative. What this means is that the test does not show colon cancer, when you actually do have the disease. Because the flexible sigmoidoscopy only allows the doctor to view a portion of your colon, it is possible that cancer in a part of your colon not seen on the test will be missed. A colonoscopy, which covers a larger portion of your colon, is less likely to give a false negative result.


Halpern MT, Pavluck AL, Ko CY, Ward EM. Factors Associated with Colon Cancer Stage at Diagnosis. Dig Dis Sci 2009 Jan 1. [Epub ahead of print].

Medline Plus. Colorectal Cancer. Accessed: January 19, 2009.

The American Cancer Society. After Diagnosis: Staging Colon and Rectum Cancer. Accessed: January 20, 2009.

The American Cancer Society: Learn about Colon and Rectum Cancer. Accessed: January 20, 2009.

The American Cancer Society. Should I Be Tested for Colon and Rectum Cancer? Accessed: January 15, 2009.

The National Cancer Institute: Colon and Rectal Cancer. Accessed: January 20, 2009.

  1. About.com
  2. Health
  3. Colon Cancer
  4. Colon Cancer Screening and Tests
  5. What is a Flexible Sigmoidoscopy?

©2014 About.com. All rights reserved.

We comply with the HONcode standard
for trustworthy health
information: verify here.