Flexible Sigmoidoscopy

A flexible sigmoidoscopy uses a long, flexible, lighted tube called a sigmoidoscope to view the lining of the sigmoid colon and the rectum. The procedure is used to look for early signs of cancer and can help doctors diagnose unexplained changes in bowel habits, abdominal pain, bleeding from the anus, and weight loss.

How do I prepare?

To prepare for a flexible sigmoidoscopy, the gastrointestinal tract must be emptied by following a clear liquid diet for 1 to 3 days before the procedure—similar to the preparation for colonoscopy. A laxative or an enema may also be required the night before a flexible sigmoidoscopy.

What happens during and after the procedure?

During a flexible sigmoidoscopy, with the patient lying on the left side, the doctor inserts the sigmoidoscope into the anus and slowly guides it through the rectum and into the sigmoid colon. The scope inflates the colon with air to give the doctor a better view. A small camera mounted on the scope transmits a video image from inside the colon to a computer screen, allowing the doctor to carefully examine the tissues lining the sigmoid colon and rectum. The doctor may ask the patient to move periodically so the scope can be adjusted for better viewing.

When the scope reaches the transverse colon, the scope is slowly withdrawn, while the lining of the colon is carefully examined again.

During flexible sigmoidoscopy, the doctor can remove growths called polyps using special tools passed through the scope. Polyps are common in adults and are usually harmless. However, most colon cancer begins as a polyp, so removing polyps early is an effective way to prevent cancer. If bleeding occurs, the doctor can usually stop it with an electrical probe or special medications passed through the scope.

The doctor can also take samples from abnormal-looking tissues. Called a biopsy, this procedure allows the doctor to examine the sample tissue with a microscope for signs of disease.

Tissue removal and the treatments to stop bleeding are usually painless. If polyps or other abnormal tissues are found, the doctor may suggest examining the rest of the colon with a colonoscopy.
A flexible sigmoidoscopy takes about 20 minutes. Cramping or bloating may occur during the first hour after the procedure, but usually dissipates fairly quickly.