Forward Viewing Endoscopy at the Time of ERCP: A Blinded Tandem Prospective Trial

Abstract Background and Study Aims: Currently, most endoscopists perform an ERCP with only a side-viewing endoscope. We hypothesized that given the non-forward viewing design of an ERCP endoscope, there is a significant miss rate of important findings. The aim of this study was to characterize the difference between a forward-viewing and side-viewing exam during ERCP. Patients and Methods: We conducted a blinded, tandem, single tertiary center prospective clinical trial of patients undergoing ERCP. Patients underwent a standard forward-viewing endoscope exam with one attending. Findings were clinically significant, defined as leading to management change, or non-management altering. A blinded second attending subsequently performed an ERCP with a side-viewing endoscope. Results: 163 participants were included. 69 (42.3%) patients had a finding that was found on forward-viewing exam which was not found on side viewing exam. Clinically significant findings, the primary outcome, were noted in 37 patients (22.7%) on forward-viewing endoscopic exam that were not seen on side-viewing exam. Comorbid malignancy was a statistically significant predictor of missed findings on side-viewing exam by univariate (30.4% vs 12.7%, p= 0.008) and multivariate (p= 0.027) analysis. Surgically altered anatomy was also statistically significant on univariate analysis (<0.001). Conclusions: About 23% of the patients in this blinded, tandem prospective trial had a management altering finding on forward-viewing endoscopic exam that was missed by a side-viewing endoscopic exam. These findings suggests that forward-viewing exam should be performed in conjunction with side-viewing exam during ERCP, particularly in setting of malignancy or altered anatomy. ClinicalTrials.gov number, NCT05627882.