The intent must be to reach the cecum, and scope must pass the splenic flexure to be complete.
A colonoscopy, 45378-45392 (Colonoscopy, flexible, proximal to splenic fixture ...), is intended to view at least as far as the cecum. To qualify for Medicare reimbursement, it must at least pass the splenic flexure.
A sigmoidoscopy, 45330- 45345 (Sigmoidoscopy, flexible ...), is the examination of the rectum, sigmoid colon and may include part of the descending colon.
A proctosigmoidoscopy, 45300-45327 (Proctosigmoidoscopy, rigid ...), is the examination of the rectum and sigmoid colon.