Are endoscopic measurements of colonic polyps reliable

Many clinical studies of colorectal adenomatous polyps rely on endoscopic estimation of polyp size. To examine the reliability of such measurements, we conducted a study using artificial polyps in an endoscopy teaching model. Eight experienced endoscopists estimated the size of 13 polyps in two separate sessions 2 wk apart. Endoscopic estimates of polyp size tended to be significantly lower than the true polyp size for all polyps and all endoscopists at both sessions. We also found a statistically significant difference in the magnitude of the underestimation between the first and second session (p<0.0001)