For this test, the doctor looks at the entire length of the colon and rectum with a colonoscope,
which is basically a longer version of a sigmoidoscope. It is inserted through the rectum into
the colon. The colonoscope has a video camera on the end that is connected to a display
monitor so the doctor can see and closely examine the inside of the colon. Special
instruments can be passed through the colonoscope to biopsy or remove any suspiciouslooking
areas such as polyps, if needed.