Abstract
Background: Conventional endoscopic mucosal resection (C-EMR) is limited by low en-bloc resection rates, especially for large (>20mm) lesions. Underwater EMR (U-EMR) has emerged as an alternative for colorectal polyps and is being shown to improve en-bloc resection rates. We conducted a systematic review and meta-analysis comparing the two techniques.
Methods: Multiple databases were searched through November 2022 for RCTs comparing outcomes of U-EMR and C-EMR for colorectal polyps. Meta-analysis was performed to determine pooled proportions and relative risks (RR) of R0 and en-bloc resection, polyp recurrence, resection time, and adverse events.
Results: Seven RCTs with 1458 patients (U-EMR: 739, C-EMR: 719) were included. The pooled rate of en-bloc resection was significantly higher with U-EMR vs C-EMR, 70.17% (CI 46.68-86.34) vs 58.14% (CI 31.59-80.68), respectively, RR 1.21 (CI 1.01-1.44). R0 resection rates were higher with U-EMR vs C-EMR, 58.1% (CI 29.75-81.9) vs 44.6% (CI 17.4-75.4), RR 1.25 (CI 0.99-1.6). For large polyps (>20 mm), en-bloc resection rates were comparable between the two techniques, RR 1.24 (CI 0.83-1.84).
Resection times were significantly lesser with U-EMR vs C-EMR, standardized mean difference -1.21 min (CI -2.57, -0.16). Overall pooled rates of perforation, immediate and delayed bleeding were comparable between U-EMR and C-EMR. Pooled rate of polyp recurrence at surveillance colonoscopy was significantly lower with U-EMR, than C-EMR, RR 0.62 (CI 0.41-0.94).
Conclusion: Colorectal U-EMR results in higher en-bloc resection rates, lower resection time and recurrence rates compared to C-EMR and both techniques have a comparable safety profile.