A sigmoidoscopy is a screening test in which a thin tube (sigmoidoscope) is inserted into a patient’s rectum to search for abnormalities in the last 2 feet (0.61 meters) of intestine, closest to the rectum and sigmoid colon. It can be used to look for the presence of polyps and other abnormal growths as well as bleeding, inflammation and ulcers that may indicate colorectal disorders.

The first sigmoidoscopes were rigid devices that could advance a shorter distance into the colon. However, rigid sigmoidoscopies are rarely performed today as most physicians prefer the more versatile flexible sigmoidoscopes.

A sigmoidoscopy is similar to another procedure called a colonoscopy. The instrument used in a sigmoidoscopy (sigmoidoscope) is shorter than the instrument used in a colonoscopy (colonoscope). The advantage of sigmoidoscopy is that it is less invasive than a colonoscopy. However, a sigmoidoscopy cannot examine as much of the colon as a colonoscopy and unlike colonoscopy patients who are usually sedated, sigmoidoscopy patients may be more aware of discomfort from the procedure.

Sigmoidoscopies are often recommended as a screening tool for patients who are not at high risk for colorectal disorders, whereas the more thorough colonoscopy may be used for patients at higher risk for these illnesses. Patients should weigh the relative advantages and disadvantages of each type of procedure and consult with a physician about which test is most appropriate.

Proper preparation is critical to the success of a sigmoidoscopy. Patients must closely adhere to their physician’s recommendations when preparing for the test. It is particularly important to follow any dietary restrictions. Failure to do so can affect test results and may result in a need to retake the test.

Sigmoidoscopies are safe procedures that usually result in only minor discomfort for the patient. In rare cases, a sigmoidoscopy may lead to perforation (a hole) in the colon. Other potential harm to the colon includes bleeding, abdominal pain and infection.