Environmental Impact of Conventional Versus Underwater Endoscopic Mucosal Resection for Colorectal Lesions: A Procedure‐Based Life Cycle Assessment With Pooled Effectiveness Estimates

ABSTRACT Objectives The environmental impact of endoscopic techniques remains poorly defined. We compared procedure‐related environmental outcomes between conventional endoscopic mucosal resection (EMR) and underwater EMR (U‐EMR) for colorectal lesions. Methods In this prospective pilot procedure‐based life cycle assessment of the resection phase, 10–25‐mm colorectal lesions underwent EMR or U‐EMR across three endoscopy units. Outcomes included global warming potential (GWP, kg CO 2 ‐equivalent/procedure), waste, life‐cycle water consumption, fossil resource scarcity, and terrestrial acidification. Exploratory GWP per en bloc resection was estimated using pooled randomized‐trial and pilot‐cohort data. Results Forty‐nine procedures were included: 23 EMR and 26 U‐EMR. En bloc resection was achieved in 56.5% of EMR and 69.2% of U‐EMR, and R0 resection in 52.2% and 69.2%. Mean GWP was significantly lower with U‐EMR than EMR (1.92 ± 0.54 vs. 2.42 ± 0.50 kg CO 2 ‐eq; p = 0.002), corresponding to a reduction of 0.50 kg CO 2 ‐eq per procedure and 50 kg CO 2 ‐eq per 100 procedures. U‐EMR was associated with lower waste generation (324.0 ± 78.3 vs. 407.3 ± 72.0 g; p < 0.001), water consumption (0.56 ± 0.17 vs. 0.77 ± 0.20 m 3 ; p < 0.001), fossil resource scarcity (0.33 ± 0.10 vs. 0.40 ± 0.09 kg oil‐eq; p = 0.007), and terrestrial acidification (0.0052 ± 0.0018 vs. 0.0068 ± 0.0018 kg SO 2 ‐eq; p = 0.003). Findings were consistent across scenario and uncertainty analyses. In the meta‐analysis‐based model, GWP per en bloc resection was lower with U‐EMR than EMR (2.59 vs. 3.51 kg CO 2 ‐eq), corresponding to a 26.3% relative reduction. Conclusions U‐EMR was associated with lower procedure‐related environmental burden than conventional EMR, persisting after normalization for en bloc resection. Trial Registration No. 165/26