Sizing of Polyp Illustrations Differs by Endoscopists’ Gender and Improves With a Measurement Reference

Colorectal cancer surveillance intervals by colonoscopy are based on the size and number of polyps removed. Evidence suggests endoscopists’ estimation of polyp size is often inaccurate, but the differences by endoscopists’ characteristics have not been reported. This study assesses endoscopists’ accuracy of measuring polyp illustrations, the effect of endoscopists’ characteristics, and the impact of having a measurement reference. Endoscopists in a community-based, gastroenterology practice estimated the size of several illustrations in a booklet. One month later, they estimated the size of illustrations with a provided measurement reference. Accuracy was defined as no difference between estimated and actual value. Endoscopists were accurate in sizing only 15% of the time, with a tendency toward undersizing. Female endoscopists, those with less than 10 years in practice and those with lower adenoma detection rates, were more likely to undersize polyps. Accuracy of measuring the polyp illustrations increased to 50% (p <.01) with the measurement reference. The improvement in accuracy was seen across endoscopists’ demographic groups. Endoscopists had poor accuracy of measuring polyp illustrations. Almost universally, endoscopists tended to undersize the polyp illustrations. Accuracy improved significantly with the use of a polyp-measuring guide, particularly when considering important surveillance thresholds of 5 and 10 mm.