Six hundred thirty-two patients were referred to the Colorectal Clinic from February 1983 to February 1986 for screening with the Pentax 65 cm flexible
sigmoidoscope. Forty-nine of these patients (8 percent) had
adenomatous polyps. There were 27 males and 22 females. The mean distance examined by the 65 cm flexible
sigmoidoscope was 55 cm. Five patients were excluded from analysis, leaving 44 patients who underwent colonoscopy to the cecum. At the time of colonoscopy, 15 of the 44 patients (34 percent) had one or more
adenomatous polyps beyond reach of the 65 cm flexible
sigmoidoscope. The remaining 29 patients who underwent colonoscopy had no
polyps beyond reach of the 65 cm flexible
sigmoidoscope. Thirty
adenomatous polyps, one invasive
carcinoma of the ascending colon, and one hyperplastic
polyp were found in these 15 patients. In summary, 34 percent of patients found to have
adenomatous polyps within reach of the 65 cm flexible
sigmoidoscope harbored one or more
adenomatous polyps in the proximal colon at the time of colonoscopy. A positive 65 cm flexible
sigmoidoscope examination requires colonoscopy to identify and remove proximal premalignant lesions, thereby aborting the
polyp-
cancer sequence.