Introduction: Electrohydraulic lithotripsy (EHL) is an endoscopic technique used to disrupt and remove gallstones. EHL is typically performed under direct vision of cholangioscopy. Some patients require multiple procedures for complete clearance, which can be burdensome in time, cost, and available expertise. Our aim is to identify patient and procedural factors that may contribute to needing multiple EHL sessions to guide patient and provider expectations.
Methods: A multicenter chart review was conducted among 6 academic centers. 403 ERCP procedures with EHL were identified, representing 310 patients, of which 60 needed at least one repeat procedure. Continuous variables were described as mean ± Standard deviation (SD), categorical variables were described as proportions or percentages. Continuous variables were compared using t-test. Bivariate analysis was performed to assess association of different covariates with the outcome: “repeat procedure”, and a multivariate logistic regression model was then constructed for this outcome. For patients who had repeat procedures, only variables related to the index procedure were taken into account. Factors such as number of stones, stone impaction, stone location, altered anatomy, hospitalization during procedure, presence of biliary stent at procedure start, and quality of image during cholangioscopy were evaluated.
Results: Of 310 patients, 250 (81%) had one EHL procedure and 60 (19%) had at least one repeat procedure. Mean age was 62 ± 18.4 and 55% were women. The median time between consecutive procedures was 60 (35-99) days. On univariable analysis, size of the largest stone, being a smoker, and having hepatolithiasis was associated with needing repeat procedures, while on multivariable analysis only size of the largest stone was predictive of needing repeat procedures (Table 1). The median size of the largest stone for those that did not need repeat procedures was significantly lower than for those who did (12.5mm (10-18) versus 20mm (15-25), p<0.001).
Conclusion: Of several evaluated factors, large stone size was the only one found to be predictive of needing multiple procedures. This guides patient expectations around the likelihood of needing repeat EHL procedure(s) and may have treatment implications for a physician’s approach.

Table 1: Clinically relevant factors associated with needing repeat procedures. Only variables that were significantly associated (p-value<0.05) with each outcome on univariable logistic regression are included in the corresponding multivariable logistic regression. OR: Odds ratio. N/A: Not applicable. Variables that were included in univariable logistic regression and found to be non-significant include: gender age, number of stones, impacted stones, pre-existing biliary stricture, percutaneous drain, altered anatomy, pre-procedure hospitalization, prior cholecystectomy, pre-procedure antibiotics.

Paul Yoon

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