Sedation. Colonoscopy is performed by placing a long, flexible tube along the entire colon and rectum via the anus. While people dread this, it is painless when done under sedation. The worst part is the day before when the "prep" is taken to purge the system. Although unpleasant, this will find polyps before they turn into cancers, thus saving one from major surgery. If you're 50, "get 'er done".
Outpatient. After an oral bowel prep, patients are sedated while a lighted flexible sope is inserted in the anus and guided through the entire colon under visualization. Polyps can be removed or biopsies performed.