Accuracy of Visual Estimation for Measuring Colonic Polyp Size: A Systematic Review and Meta-Analysis

Measurement of colorectal polyps is typically performed through visual estimation, which is prone to bias. Studies have evaluated the accuracy of visual estimation and utility of assistive tools, but results have been mixed. The aim of this study was to clarify the accuracy of visual estimation as a measurement tool and the benefits of artificial intelligence.

MEDLINE and Embase were searched through October 2024. Extraction and quality assessment were performed independently by 2 authors. The primary outcome was the pooled absolute mean difference in size between visual estimation and control. Secondary outcomes included subgroup analysis of expert vs trainee status, accuracy of artificial intelligence, study origin (East vs West), comparator type, definition of accuracy, polyp size, direction of estimation, and image type.

Thirty-five studies with 42,964 polyp measurements were included in our analysis. All studies were of high quality, and there was no evidence of publication bias. The pooled absolute mean difference from comparator was 1.68 mm (confidence interval 1.21-2.15) with high variability explained by differences in the comparator, direction of estimation, image type, and size of the polyp. Overall accuracy was 60% with high variability as well, with increased accuracy with video displayed over photographs. Artificial intelligence improved accuracy with an odds ratio of 7.46.

Visual estimation is an inaccurate and imprecise way to measure colorectal polyps. Further research is needed to determine the impact on clinical outcomes related to colorectal cancer. Investment in new technology to aid in polyp measurement is an important next step.