I have a history of colon polyps in my family, so I have to go for a colonoscopy every 10 years. I am over 50, and my doctor recommended I come in once every 10 years for this procedure as long as they do not find any polyps or cancers.
I asked him why I couldn’t just get a sigmoidoscopy, because it involves a shorter tube. He told me that a colonoscopy can examine the whole colon, but a sigmoidoscopy only looks at the rectum and the nearby section of colon. He also said the about 50% of colon cancers and colon polyps are found in the cecum, the ascending colon, and the transverse colon. These are all in the upper colon, which cannot be reached by a sigmoidoscope.