title: Negative screening colonoscopy after a positive guaiac faecal occult blood test: not a contraindication to continued screening.
abstract: OBJECTIVE
  In guaiac faecal occult blood test (gFOBT) screening at least 50% of positive individuals will have a colonoscopy negative for colorectal neoplasia. The question of continuing screening in this group has not been addressed.
  
  
  METHODS
  Data on participants aged 50-69 years with a positive gFOBT result and a negative colonoscopy were followed through the biennial screening pilot conducted between 2000 and 2007 in Scotland.
  
  
  RESULTS
  In the first screening round, 1527 colonoscopies were negative for neoplasia. 1300 were re-invited in the second round, 905 accepted, and 157 had a positive gFOBT result, giving a positivity rate of 17.4%. Colonoscopy revealed 20 subjects with adenoma and six with invasive cancer. In the third screening round 1031 were invited for a third time and 730 accepted: 55 had a positive gFOBT test, giving a positivity rate of 7.5%. In this group, six colonoscopies revealed adenomas but there were no cancers diagnosed. In the third screening round, 108 individuals had had two positive gFOBT results and two subsequent negative colonoscopies. Eighty-four were invited for a third gFOBT, 66 accepted and 19 (25.6%) had a positive result none of whom had an adenoma or carcinoma.
  
  
  CONCLUSIONS
  These data indicate that a negative colonoscopy following a positive gFOBT is not a contraindication for further screening, although this is likely to have a low yield of neoplastic pathology after two negative colonoscopies.
authors: Department of Surgery, University of Dundee, Ninewells Hospital and Medical School, Dundee, UK.
authors: A
authors: A
authors: Carrera
authors: P L
authors: PL
authors: McClements
authors: C
authors: C
authors: Watling
authors: G
authors: G
authors: Libby
authors: D
authors: D
authors: Weller
authors: D H
authors: DH
authors: Brewster
authors: F A
authors: FA
authors: Carey
authors: C G
authors: CG
authors: Fraser
authors: R J C
authors: RJ
authors: Steele
mesh_terms: D000236:Adenoma / Q000175:diagnosis* / Q000453:epidemiology / Q000473:pathology; D000368:Aged; D003113:Colonoscopy; D015179:Colorectal Neoplasms / Q000175:diagnosis* / Q000453:epidemiology / Q000473:pathology; D005260:Female; D006138:Guaiac; D006801:Humans; D007202:Indicators and Reagents; D008297:Male; D008403:Mass Screening; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009780:Occult Blood; D011237:Predictive Value of Tests; D012606:Scotland / Q000453:epidemiology
chemical_list: D007202:Indicators and Reagents; D006138:Guaiac