Direct peroral cholangioscopy (POC) can be useful when combined with narrow-band imaging (NBI) to explore the etiologies of indeterminate biliary strictures. We evaluated the efficacy of NBI compared with that of conventional white-light imaging (WLI) during POC diagnosis of indeterminate biliary strictures.

Consecutive patients with indeterminate biliary strictures were enrolled from 2016 to 2019. The primary outcome was diagnostic accuracy, and secondary outcomes were technical success, adverse events, and visualization quality when predicting malignancy.

Seventy-one patients underwent direct POC under NBI during targeted biopsy sampling. The strictures were successfully explored and adequate biopsy samples obtained in 67 of 71 patients (94.4%). In terms of visual impression, WLI and NBI afforded 75.0% and 87.5% sensitivity, 82.9 and 91.4% specificity, and 82.8 and 91.3% accuracy, respectively. The areas under the WLI and NBI receiver-operating characteristic curves were .80 and .96 (P = .01). Under NBI, the visualization quality of surface structures, microvessels, and lesional margins was higher than that under conventional WLI (P < .05).

Direct POC under NBI effectively and accurately predicts malignancies of indeterminate biliary strictures. NBI effectively illuminated surface structures, microvessels, and lesional margins.