Variation in polyp size estimation among endoscopists and impact on surveillance intervals

Background Accurate estimation of polyp size is important because it is used to determine the surveillance interval after polypectomy. Objective To evaluate the variation and accuracy in polyp size estimation among endoscopists and the impact on surveillance intervals after polypectomy. Design Web-based survey. Participants A total of 873 members of the American Society for Gastrointestinal Endoscopy. Interventions Participants watched video recordings of 4 polypectomies and were asked to estimate the polyp sizes. Main Outcome Measurements Proportion of participants with polyp size estimates within 20% of the correct measurement and the frequency of incorrect surveillance intervals based on inaccurate size estimates. Results Polyp size estimates were within 20% of the correct value for 1362 (48%) of 2812 estimates (range 39%-59% for the 4 polyps). Polyp size was overestimated by >20% in 889 estimates (32%, range 15%-49%) and underestimated by >20% in 561 (20%, range 4%-46%) estimates. Incorrect surveillance intervals because of overestimation or underestimation occurred in 272 (10%) of the 2812 estimates (range 5%-14%). Participants in a private practice setting overestimated the size of 3 or of all 4 polyps by >20% more often than participants in an academic setting (difference = 7%; 95% confidence interval, 1%-11%). Limitations Survey design with the use of video clips. Conclusion Substantial overestimation and underestimation of polyp size occurs with visual estimation leading to incorrect surveillance intervals in 10% of cases. Our findings support routine use of measurement tools to improve polyp size estimates.