Yield of rescreening for colonic polyps using flexible sigmoidoscopy.

OBJECTIVE: To determine the yield of performing screening-flexible sigmoidoscopy 1 yr after a negative examination.
METHODS: In a flexible sigmoidoscopy screening program at a chemical factory, over a period of 3 yr, 307 sigmoidoscopies were performed by a single endoscopist in workers greater than or equal to 40 yr old. Of 202 workers screened in the first 2 yr, 32% were found to have polyps (mean age, 52.9 yr). Repeat flexible sigmoidoscopy was recommended to all workers after 1 yr, and 81 complied.
RESULTS: The mean (+/- SEM) time to follow-up was 17.0 +/- 0.7 months; of 69 workers who were negative on the first exam, five (7.2%) had a polyp at follow-up. Two of the five patients with polyps were under the age of 50. Of 12 workers who had polyps on the index exam and requested a repeat flexible sigmoidoscopy a yr later, four (33%) again had a polyp. Colonoscopy had been performed in the time interval between the two sigmoidoscopies in 10 of the 12 workers; four (33%) had recurrent polyps.
CONCLUSIONS: We conclude that a significant yield of polyps (7.2%) may be found on repeat flexible sigmoidoscopy despite a negative examination within the prior 2 yr. Although the overall yield in this study population was reduced from 32% to 7% by repeat screening, this study supports older American Cancer Society guidelines i.e., to repeat flexible sigmoidoscopy at 1 yr in patients whose first examination was negative. Because half of the positive workers were under age 50, this study also suggests that the American Cancer Society age cutoff may be too stringent.