ERCP in patients with Billroth II gastrectomy remains technically challenging. Although both the conventional side-viewing duodenoscope and the forward-viewing endoscope with a distal cap are used in this setting, comparative evidence specifically assessing the role of the distal cap is limited. This study represents the first systematic review and meta-analysis comparing the efficacy and safety of cap-assisted forward-viewing endoscopy versus side-viewing duodenoscopy for ERCP in patients with Billroth II anatomy.

A comprehensive literature search was conducted in PubMed, Embase, Scopus, and the Cochrane Library from inception through October 2025. Comparative observational studies evaluating ERCP performed with a cap-assisted forward-viewing endoscope versus a side-viewing duodenoscope in adult patients with prior Billroth II gastrectomy were included, with a focus on efficacy and safety outcomes. Pooled risk ratios (RRs) with 95% CIs were calculated using random-effects models, and heterogeneity was assessed using the I ² statistic. Analyses were performed on both a per-patient and per-procedure basis.

Seven observational studies, comprising approximately 350 patients and 727 procedures, were included. No statistically significant differences were observed between the 2 approaches in terms of biliary cannulation success and clinical success. Overall adverse event rates were comparable between groups. Post-ERCP pancreatitis showed a nonsignificant numerical increase with cap-assisted forward-viewing endoscopy in both the procedure-level analysis (14.5% vs 6.7%; RR, 2.11; 95% CI, 0.90-4.92; P = .08; I ² = 0%) and the patient-level analysis (10.2% vs 4.5%; RR, 2.23; 95% CI, 0.66-7.54; P = .20; I ² = 0%). Conversely, perforation rates were low and did not differ significantly, with a nonsignificant numerical reduction favoring cap-assisted forward-viewing endoscopy in procedure-level (1.1% vs 1.2%; RR, 0.70; 95% CI, 0.11-4.34; P = .70; I ² = 0%) and patient-level analyses (1.7% vs 0.9%; RR, 0.88; 95% CI, 0.09-8.30; P = .91; I ² = 0%). Findings were consistent across per-patient and per-procedure analyses.

Cap-assisted forward-viewing endoscopy and side-viewing duodenoscopy showed similar efficacy for ERCP in patients with Billroth II gastrectomy. Although no statistically significant differences were observed in major adverse events, these findings should be interpreted with caution because limited statistical power may have obscured clinically relevant differences. Current evidence does not support a firm conclusion regarding equivalence or superiority of either approach, and larger comparative studies are needed to better define their relative efficacy and safety.