What is a sigmoidoscopy?
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 detect inflamed tissue, abnormal growths or polyps, and ulcers. The procedure can help diagnose changes in bowel habits, abdominal pain, bleeding from the anus, and 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 doctor 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 doctor’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 tract must be emptied. This is done by following a clear liquid diet for 1 to 3 days before the procedure. Patients should not drink beverages containing red or purple dye. Certain medications should not be taken before the exam. Your doctor 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 and able to be clearly visualized by the provider.
How is this test performed?
During the exam, patients lie on their side on an examination 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 on the screen. The provider may ask the patient to move periodically 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 to perform the biopsy or further evaluate the rest of the colon.
A flexible sigmoidoscopy takes about 5-20 minutes. You will be awake during the procedure.
What to expect after your sidmoidoscopy?
Cramping or bloating may occur after the test. You can return to your normal activity and diet after the test.
How do you receive the results of your sigmoidoscopy?
The provider will typically talk to you about the findings of the test before you go home. Any biopsies that were taken will be sent to a pathologist to be reviewed. The results of this are usually available in 7-10 days. Your care provider will be able to discuss these results with you.
When to contact your 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.
Patients who develop any of these side effects should contact their doctor immediately:
- Severe abdominal pain
- 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