Endoscopic overestimation of colorectal polyp size

Background and aims: Polyp size ≥ 1 cm triggers more frequent colonoscopic surveillance, yet size is typically based on subjective endoscopic estimates. We sought to compare contemporary assessments of polyp size by endoscopic estimation and pathology measurement.

Methods: Colonoscopy and pathology reports were reviewed from the 2012 medical records at a large institution. Only polyps resected in toto with both endoscopic estimates and pathology measurements were included. Pathology measurements were considered the criterion standard. Factors affecting endoscopic miscall rates were assessed by multivariate analyses.

Results: From 6067 polyps resected, both endoscopic and pathology sizes were available on 1528. Distribution of polyp size appraised by endoscopy but not by pathology revealed modal clustering, particularly around 1 cm. Among 99 polyps endoscopically called 1 cm, 72% were <1 cm on pathology. Of all 222 polyps estimated as ≥ 1 cm on endoscopy, 46% were <1 cm on pathology; of 1306 polyps estimated as <1 cm, 3.9% were ≥ 1 cm on pathology. By histology, 39% of adenomatous, 59% of sessile serrated, and 73% of hyperplastic polyps were overcalled; P = .008. By configuration, 34% of pedunculated, 49% of sessile, and 61% of flat polyps were overcalled; P = .014. Endoscopic overestimation was more common in women (54%) than in men (40%) (P = .03) and with proximal (56%) than distal (40%) sites; P = .02. Miscall rates were unaffected by endoscopist covariates.

Conclusions: Substantial discordance exists between endoscopic and pathology-based assessments of polyp size. Almost half of polyps called advanced on endoscopic estimates of size ≥ 1 cm fell below this threshold on actual pathology measurements.