To address the primary aim, differences in duration of stent patency, the Kaplan-Meier method will be used to estimate stent patency in each group and the log-rank test will be used for an unadjusted comparison between groups. Then a Cox proportional hazard model will be constructed to compare time to stent occlusion adjusted for important potential confounders. Stent patency will be calculated in days and will represent the interval between the time of stent insertion and the time of its replacement or the death of the patient with concomitant cholangitis.