title: Is colonoscopy indicated for small adenomas found by screening flexible sigmoidoscopy?
abstract: BACKGROUND
  There is controversy over whether patients who have a small tubular adenoma on screening flexible sigmoidoscopy should undergo colonoscopic examination of the proximal colon.
  
  
  OBJECTIVE
  To prospectively determine the prevalence of advanced polyps in the proximal colon among patients who have small adenomas on screening sigmoidoscopy.
  
  
  METHODS
  Prospective cohort study.
  
  
  METHODS
  A health maintenance organization and a Veterans Affairs medical center.
  
  
  METHODS
  Asymptomatic patients older than 50 years of age who had no risk factors for colon cancer and underwent sigmoidoscopy.
  
  
  METHODS
  At the time of sigmoidoscopy, all polyps were biopsied and characterized. All patients with distal adenomas were offered colonoscopy.
  
  
  METHODS
  The size and histology of polyps identified by sigmoidoscopy and colonoscopy were noted. Polyps were considered advanced if they were larger than 10 mm or were tubulovillous, villous, or malignant. The prevalence of advanced proximal polyps was determined, and patients were stratified by the size and number of distal polyps found by sigmoidoscopy.
  
  
  RESULTS
  Among 4490 patients who underwent sigmoidoscopy, a neoplastic lesion was detected in 401 (8.9%) and colonoscopy was done in 301 (75%). Of 90 patients with a single tubular adenoma 1 to 5 mm in diameter in the distal colon, 0% (95% CI, 0.0% to 4.0%) had an advanced proximal polyp compared with 5.4% (CI, 2.4% to 10.4%) of those who had multiple distal polyps 1 to 5 mm or 6 to 10 mm in diameter and 7.9% (CI, 2.6% to 17.6%) of those who had advanced distal polyps (P = 0.013 for trend). The low-risk group with a single tubular adenoma 1 to 5 mm in diameter represented 44% of all patients with distal adenomas or cancers found at flexible sigmoidoscopy.
  
  
  CONCLUSIONS
  Among patients undergoing screening sigmoidoscopy, those with single tubular adenomas of 5 mm or less had a low prevalence of advanced proximal polyps. These patients may not benefit from colonoscopy.
authors.affiliation: Brigham and Women's Hospital, Boston, Massachusetts, USA.
authors.forename: M B
authors.initials: MB
authors.lastname: Wallace
authors.forename: J A
authors.initials: JA
authors.lastname: Kemp
authors.forename: Y M
authors.initials: YM
authors.lastname: Trnka
authors.forename: J M
authors.initials: JM
authors.lastname: Donovan
authors.forename: F A
authors.initials: FA
authors.lastname: Farraye
mesh_terms: D000236:Adenoma / Q000175:diagnosis* / Q000473:pathology; D000368:Aged; D003110:Colonic Neoplasms / Q000175:diagnosis* / Q000473:pathology; D003113:Colonoscopy / Q000191:economics; D003365:Costs and Cost Analysis; D005260:Female; D006801:Humans; D007417:Intestinal Polyps / Q000175:diagnosis* / Q000473:pathology; D016015:Logistic Models; D008297:Male; D008403:Mass Screening; D008875:Middle Aged; D011446:Prospective Studies; D012811:Sigmoid Neoplasms / Q000175:diagnosis* / Q000473:pathology; D012812:Sigmoidoscopy / Q000191:economics