Endoscopic Polyp Size Measurement Using a Laser-Based Sizing Probe: A Pilot Study

Abstract: Background and aims: Accurate measurement of colorectal polyp size is important for planning resection and post-polypectomy surveillance. This study evaluated a through-the-scope laser-based probe for polyp sizing during colonoscopy. Methods: A prospective pilot study was conducted at CHUM, where polyps were measured using a laser-based probe. The primary outcome was the accuracy of the laser-based probe, defined as mean bias with microscopic sizing as the reference standard. Secondary outcomes included agreement with the reference, implementation rate, technical success rate, reasons for failure, and per-polyp measurement time. Results: Among 323 patients, 402 colorectal polyps were detected. Laser-based measurement was attempted in 237 polyps (59.0% 237/402; 95% CI: 54.0–63.8), of which 149 had microscopic reference measurements. The technical success rate was 40.9% (97/237; 95% CI, 34.6–47.5), with a mean measurement time of 1:35. Accounting for non-en-bloc resections, 41 of 149 polyps (27.5%; 95% CI, 20.7–35.5) had paired laser–microscopy measurements for the primary analysis. Laser-based measurement showed minimal bias (−0.10 mm; 95% CI, −0.30 to 0.10; P = 0.328), meeting the prespecified noninferiority margin of 0.4 mm. Agreement with the reference standard was high (ICC = 0.91; 95% CI, 0.83–0.95), with near-perfect categorical concordance (κ = 0.85) and 95.1% classification accuracy (39/41; 95% CI, 82.2–99.2). Bland–Altman limits of agreement ranged from −1.34 mm to 1.14 mm. Conclusions: Laser-based measurement provided accurate polyp sizing when obtained. However, technical success was limited by longer measurement times and device issues.