Module 2. Screening and Diagnosis

What is the difference between a flexible sigmoidoscopy and a colonoscopy?

Colonoscopy and flexible sigmoidoscopy are tests that both screen for colon cancer; however they differ in which areas of the colon they can see. Flexible sigmoidoscopy only examines the rectum and lower third of the colon. Whereas, a colonoscopy examines the rectum and the entire length of the colon. A disadvantage of sigmoidoscopy is that any polyps or abnormalities in the unexamined upper part of the colon will be missed. Another difference is the type of bowel prep that is required beforehand. Flexible sigmoidoscopy requires the patient to do an enema, while a colonoscopy requires full bowel prep. Regardless of which test is performed, good bowel prep is critical for the doctor to be able to see the colon clearly. Talk to your doctor about which test is right for you.
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