There is only one medical difference between a colonoscopy and sigmoidscopy. A colonoscopy examines the entire colon where a sigmoidscopy only examines the left side of the colon. One other non-medical difference is that a colonoscopy is a little bit more painful than a sigmoidscopy, explains Scripps Health.
Both of these tests are used to detect colon cancer by inserting a tiny camera into a person's colon. Because a colonoscopy views the entire colon, it's a little more painful. There is one other minor non-medical difference. Unless there is a history of colon cancer in your family, a colonoscopy is only needed every 10 years, where a sigmoidscopy needs to be repeated every 5 years, explains Scripps Health.