Flexible sigmoidoscopy is a procedure used to see inside the sigmoid colon and rectum. It can detect inflamed tissue, abnormal growths, and ulcers. 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.
The sigmoid colon is the last one-third of the colon. The colon comprises three main parts: the ascending colon, the transverse colon, and the sigmoid colon—sometimes called the descending colon. The colon absorbs nutrients and water and forms stool.
The rectum is about 6 inches long and connects the sigmoid colon to the anus. Stool leaves the body through the anus. Muscles and nerves in the rectum and anus control bowel movements.
Flexible sigmoidoscopy differs from colonoscopy because it enables the doctor to see only the sigmoid colon, whereas colonoscopy allows the doctor to see the entire colon. Colonoscopy is the preferred screening method for cancers of the colon and rectum; however, to prepare for and perform a flexible sigmoidoscopy usually requires less time.
- One or more enemas are performed about 2 hours before the procedure to remove all solids from the sigmoid colon.
- In some cases, the entire gastrointestinal tract must be emptied—similar to the preparation for colonoscopy.
- A sigmoidoscope transmits a video image from inside the colon to a computer screen.
- A doctor can biopsy abnormal-looking tissues during a flexible sigmoidoscopy.
- Polyps can be removed using special tools passed through the sigmoidoscope.
- 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.