A sigmoidoscopy is a minimally invasive diagnostic procedure that gathers information on intestinal symptoms and looks for the presence of abnormal tissue in the rectum and sigmoid colon. Sigmoidoscopy differs from colonoscopy in that your doctor is limited to examining only your rectum and the lower part of the large intestine, which is called the sigmoid colon. In a colonoscopy, the entire large intestine is examined. The other difference between the two procedures is that no sedation is needed for a sigmoidoscopy.

Types of Procedures

There are two types of sigmoidoscopy procedures -- flexible sigmoidoscopy and rigid sigmoidoscopy. The difference between the two has to do with the type of scope used, either a flexible or rigid tube. Rigid sigmoidoscopy is now rarely used because of the improved technology of flexible sigmoidoscopy. Some doctors may still use the rigid sigmoidoscopy as a quick way to gain basic diagnostic information.

Preparation for a sigmoidoscopy procedure varies. You may be required to begin preparation on the day prior to the test. If this is the case, you will be asked to refrain from eating solid foods and to use laxatives to ensure that your colon will be empty on the day of the test. In other cases, enemas may be given a couple of hours before the test to clean out the sigmoid colon.

During the procedure, you will be asked to lie down on your left side. A short, lighted tube, called a sigmoidoscope, is inserted into the rectum. The tube fills the area with air and takes a video image that your doctor can examine. The scope can remove polyps and take biopsy samples of abnormal tissue, both of which will then be sent to a laboratory to rule out the presence of cancer.

The procedure takes approximately 20 minutes.

Also Known As: Proctoscopy, Proctosigmoidoscopy