title: Variable interpretation of polyp size by using open forceps by experienced colonoscopists.
abstract: BACKGROUND
  Endoscopic measurement of colorectal polyps by using open forceps is commonly used in clinical trials but is subject to several sources of error.
  
  
  OBJECTIVE
  Assess error rates in polyp size determination with open forceps at the step of measurement after the forceps are aligned on the polyp.
  
  
  METHODS
  This was a prospective assessment of 49 gastroenterologists who received training on 10 photographs of polyps with aligned forceps and then measured 10 additional test polyps from photographs. One of the test photographs was excluded because of incorrect forceps alignment.
  
  
  METHODS
  Data analyzed at an academic medical center.
  
  
  METHODS
  Photographs displayed in a webinar.
  
  
  METHODS
  Description of rates of accurate measurements, including the fraction correct within 50% and 25% margins of error.
  
  
  RESULTS
  A total of 37% of all measurements were correct to the exact millimeter, 34% were larger, and 29% smaller compared with the reference standard. A total of 47 of 49 doctors measured all 9 polyps within 50% of the reference standard, and 21 measured all 9 correctly within a 25% error margin.
  
  
  CONCLUSIONS
  Other potential sources of error in open forceps measurement were not evaluated.
  
  
  CONCLUSIONS
  Open forceps polyp size determination is subject to error at the step of using the fully aligned forceps as a scale for measurement. A margin of error of 50% up or down is needed to prevent this step in size determination from causing errors in polyp matching in clinical trials comparing diagnosis-only imaging to colonoscopy.
authors.affiliation: Division of Gastroenterology/Hepatology, Indiana University Health, Indianapolis, Indiana, USA.
authors.forename: Douglas K
authors.initials: DK
authors.lastname: Rex
authors.affiliation: Given Imaging Ltd, Yoqneam, Israel.
authors.forename: Raphael
authors.initials: R
authors.lastname: Rabinovitz
mesh_terms: D003111:Colonic Polyps / Q000473:pathology*; D003113:Colonoscopy / Q000295:instrumentation; D061827:Dimensional Measurement Accuracy; D006801:Humans; D015588:Observer Variation; D011446:Prospective Studies; D012002:Rectal Diseases / Q000473:pathology*