title: Screening flexible sigmoidoscopy in a low-risk, highly screened population.
abstract: BACKGROUND
  The efficacy of screening flexible sigmoidoscopy in patients with a prior history of a negative screening sigmoidoscopy has not been previously studied.
  
  
  METHODS
  Charts from 866 consecutive asymptomatic patients undergoing baseline or rescreening flexible sigmoidoscopy were reviewed. Any previously screened patient with a history of polyps was excluded from the study. Findings on sigmoidoscopy, including size, location, and histopathology of lesions and number of prior examinations, if any, were recorded.
  
  
  RESULTS
  Polyps were found in only 12 of 866 patients (1.4%). The effect of prior screening was significant. Ten of 414 (2.4%) patients who had not undergone prior screening sigmoidoscopy were found to have polyps. In contrast, only two of 452 (0.4%) patients who had undergone prior screening were found to have polyps.
  
  
  CONCLUSIONS
  Screening flexible sigmoidoscopic examinations provided a low positivity yield in this study, a finding that is likely explained by the exclusion of previously screened patients with a history of polyps and by the significant number of previously screened patients. The relation between the prevalence of lesions and the patients' previous examination statuses suggests that multiple screenings for asymptomatic, low-risk patients at 3- to 5-year intervals as recommended by the American Cancer Society may be unnecessary.
authors.affiliation: Department of Family Practice, Kaiser Permanente Medical Center, Los Angeles, CA 90027.
authors.forename: M S
authors.initials: MS
authors.lastname: Sakamoto
authors.forename: J H
authors.initials: JH
authors.lastname: Hara
authors.forename: J M
authors.initials: JM
authors.lastname: Schlumpberger
mesh_terms: D000368:Aged; D003111:Colonic Polyps / Q000175:diagnosis; D015179:Colorectal Neoplasms / Q000517:prevention & control*; D005260:Female; D006801:Humans; D008297:Male; D008403:Mass Screening; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors; D012812:Sigmoidoscopy; D013997:Time Factors