What is a sigmoidoscopy?
A sigmoidoscopy, or "flexible sigmoidoscopy," is a medical test that uses a thin, flexible tube with a light and camera on it to see inside the sigmoid colon and rectum. The sigmoid colon is the last one-third of the colon. It is sometimes called the descending colon.
Flexible sigmoidoscopy can find inflamed tissue, abnormal growths or polyps, and ulcers. The procedure can help diagnose:
- Changes in bowel habits.
- Abdominal (belly) pain.
- Bleeding from the anus.
- Weight loss.
A flexible sigmoidoscopy is different than a colonoscopy. Flexible sigmoidoscopy enables the provider to see only the sigmoid colon. A colonoscopy allows the provider to see the entire colon. Colonoscopy is the preferred method when screening for cancers of the colon and rectum. However, it takes less time to complete a sigmoidoscopy and it can be done in some primary care provider's offices.
How do I prepare for a sigmoidoscopy?
You will be given specific instructions to prepare for a flexible sigmoidoscopy. Often, one or more enemas are performed about 2 hours before the procedure. This is to remove all solids from the sigmoid colon. A laxative or an enema may also be required the night before the procedure.
In some cases, the entire gastrointestinal (GI) tract must be emptied. This is done by following a clear liquid diet for 1 to 3 days before the procedure. You should not drink beverages that have red or purple dye. Certain medications should not be taken before the exam. Your care team will tell you which medications not to take.
It is important to follow all directions given to you so that your colon is clear of stool (bowel movements) and able to be clearly seen by the provider.
How is this test done?
During the exam, you will lie on your side on an exam table. The provider inserts a long, flexible, lighted tube called a sigmoidoscope, or scope, into the anus. This is then slowly guided through the rectum and into the sigmoid colon. The scope inflates the colon with air to give the provider a better view. A small camera mounted on the scope transmits a video image from inside the colon to a computer screen. The provider looks for signs of disease in the sigmoid colon on the screen. The provider may ask you to move every so often so the scope can be adjusted for better viewing.
The provider may find growths, called polyps, during the exam. In some cases, these can be removed using special tools passed through the sigmoidoscope. In some cases, you will need to have a colonoscopy at a later date to do a biopsy or to further see the rest of the colon.
A flexible sigmoidoscopy takes about 5-20 minutes. You will be awake during the procedure.
What should I expect after my sigmoidoscopy?
Cramping or bloating may happen after the test. You can return to your normal activity and diet after the test.
How do I receive the results of my sigmoidoscopy?
The provider will often talk to you about the findings of the test before you go home. 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 care provider will be able to discuss these results with you.
When should I contact my care team?
Bleeding can occur if any tissue is removed during the procedure. It will also occur if the large intestine is punctured during the exam. These events rarely occur, but are serious.
If you have any of these side effects, you should call your provider right away:
- Severe abdominal (belly) pain.
- Fever or chills.
- Bloody bowel movements.
- Dizziness or weakness.
If you are unable to contact your care team, you should call 911 or go to a local emergency room.
Mayo Clinic. Flexible sigmoidoscopy. 2018. Found at: https://www.mayoclinic.org/tests-procedures/flexible-sigmoidoscopy/about/pac-20394189
National Institute of Diabetes and Digestive and Kidney Diseases. Flexible Sigmoidoscopy. 2016. Found at: https://www.niddk.nih.gov/health-information/diagnostic-tests/flexible-sigmoidoscopy