A sigmoidoscopy, or "flexible sigmoidoscopy," is a medical test that uses a thin, flexible tube with a light and camera to see inside the sigmoid colon and rectum. The sigmoid colon is the last one-third of your colon. It is sometimes called the descending colon.
Why would I need a sigmoidoscopy?
Flexible sigmoidoscopy can find inflamed tissue, abnormal growths or polyps, and ulcers. This test can also help diagnose:
- Changes in bowel habits such as diarrhea or constipation.
- Abdominal (belly) pain.
- Bleeding from the anus.
- Weight loss.
A flexible sigmoidoscopy is different than a colonoscopy. Flexible sigmoidoscopy allows your provider to see only the sigmoid colon. A colonoscopy allows your provider to see the entire colon. Colonoscopies are the preferred method when screening for cancers of the colon and rectum. However, it takes less time to do a sigmoidoscopy and they can be done in some primary care provider's offices.
How do I prepare for a sigmoidoscopy?
Your provider will give you instructions on how to prepare for the test. You may be asked to take a laxative or an enema before the test. This is to remove all solids from your sigmoid colon.
In some cases, the entire gastrointestinal (GI) tract must be emptied. This is done by not eating and following a clear liquid diet for 1 to 3 days before the test.
Certain medications, vitamins, and supplements should not be taken before the test. Your care team will tell you which medications not to take. It is important to follow the instructions given to you so that your colon is empty and can be seen clearly by your provider.
How is this test done?
During the test, you will lie on your side on an exam table. Your provider will insert the long, flexible, lighted tube, sigmoidoscope or scope, into your anus (rectum or bottom). It is slowly guided through your rectum and into your sigmoid colon.
The scope inflates the colon with air to give your provider a better view. The video image seen by the camera mounted on the scope will show the inside of your colon on a computer screen. Your provider will look for signs of disease in the sigmoid colon on the screen. You may be asked to move your body into different positions so the scope can be adjusted for better viewing.
Your provider may find growths, called polyps, during the exam. In some cases, these can be removed using special tools passed through the sigmoidoscope. A flexible sigmoidoscopy takes about 5-20 minutes. You will be awake during the procedure.
If your provider needs to do a biopsy or needs to see the rest of your colon, they may ask you to schedule a colonoscopy.
What should I expect after my sigmoidoscopy?
You can return to your normal activity and diet after the test. You may have cramping or bloating after the test. If a biopsy was done or a polyp was removed during the test you may have light bleeding or blood in your bowel movements (poop) for a day or two. This is normal.
How do I receive the results of my sigmoidoscopy?
Your provider will either talk to you about the findings of the test before you go home, or they will call you in the days after the test. Any biopsies that were taken will be sent to a pathologist (a doctor who looks at biopsy samples under a microscope) to be reviewed. The results of the biopsy are usually available in 7-10 days. Your provider will discuss these results with you.
When should I contact my care team?
If you have any of these side effects, you should call your provider right away:
- Abdominal (belly) pain or swelling.
- Fever or chills.
- Bloody bowel movements.
- Dizziness or weakness.
- Not able to pass gas.
If you are unable to contact your care team, you should call 911 or go to a local emergency room.
Mayo Foundation for Medical Education and Research. (2022, March 5). Flexible sigmoidoscopy. Mayo Clinic. Retrieved August 17, 2022, from https://www.mayoclinic.org/tests-procedures/flexible-sigmoidoscopy/about/pac-20394189
U.S. Department of Health and Human Services. (2016, July). Flexible sigmoidoscopy. National Institute of Diabetes and Digestive and Kidney Diseases. Retrieved August 16, 2022, from https://www.niddk.nih.gov/health-information/diagnostic-tests/flexible-sigmoidoscopy