Comparing size measurement of colorectal polyps using a novel virtual scale endoscope, endoscopic ruler or forceps: A preclinical randomized trial

Background and Aims: Accurate polyp size measurement is important for guideline conforming choice of polypectomy techniques and subsequent surveillance interval assignments. Some endoscopic tools (biopsy forceps [BF] or endoscopic rulers [ER]) exist to help with visual size estimation. A virtual scale endoscope (VSE) has been developed that allows superimposing a virtual measurement scale during live endoscopies. Our aim was to evaluate the performance of VSE when compared to ER and BF-based measurement. Methods: We conducted a preclinical randomized trial to evaluate the relative accuracy of size measurement of simulated colorectal polyps when using: VSE, ER, and BF. Six endoscopists performed 60 measurements randomized at a 1:1:1 ratio using each method. Primary outcome was relative accuracy in polyp size measurement. Secondary outcomes included misclassification of sizes at the 5, 10, and 20mm thresholds. Results: A total of 360 measurements were performed. The relative accuracy of BF, ER, and VSE was 78.9% (95%CI=76.2-81.5), 78.4% (95%CI=76.0-80.8), and 82.7% (95%CI=80.8-84.8). VSE had significantly higher accuracy compared to BF (p=0.02) and ER (p=0.006). VSE misclassified a lower percentage of polyps >5mm as ≤5mm (9.4%) compared to BF (15.7%) and ER (20.9%). VSE misclassified a lower percentage of ≥20mm polyps as <20mm (8.3%) compared with BF (66.7%) and ER (75.0%). 25.6%, 25.5%, and 22.5% of polyps ≥10mm were misclassified as