Impact of difficult biliary cannulation on post-ERCP pancreatitis: secondary analysis of the stent versus indomethacin trial dataset

Background and Aims: Difficult biliary cannulation (DBC) is a known risk factor for developing post-ERCP pancreatitis (PEP). To better understand how DBC increases PEP risk, we examined the interplay between technical aspects of DBC and known PEP risk factors. Methods: This was a secondary analysis of a multicenter, randomized controlled trial comparing rectal indomethacin alone with the combination of rectal indomethacin and prophylactic pancreatic duct (PD) stent placement for PEP prophylaxis in high-risk patients. Participants were categorized into 3 groups: DBC with high preprocedure risk for PEP, DBC without high preprocedure risk for PEP, and non-DBC at high preprocedure risk for PEP. Results: In all, 1601 participants (84.1%) experienced DBC, which required a mean of 12 cannulation attempts (standard deviation, 10) and mean duration of 14.7 minutes (standard deviation, 14.9). PEP rate was highest (20.7%) in DBC with a high preprocedure risk, followed by non-DBC with a high preprocedure risk (13.5%), and then DBC without a high preprocedure risk (8.8%). Increasing number of PD wire passages (adjusted odds ratio [aOR], 1.97; 95% confidence interval [CI], 1.25-3.1) was associated with PEP in DBC, but PD injection, pancreatic sphincterotomy, and number of cannulation attempts were not associated with PEP. Combining indomethacin with PD stent placement lowered the risk of PEP (aOR, .61; 95% CI, .44-.84) in DBCs. This protective effect was evident in up to at least 4 PD wire passages. Conclusions: DBC confers higher PEP risk in an additive fashion to preprocedural risk factors. PD wire passages appear to add the greatest PEP risk in DBCs, but combining indomethacin with PD stent placement reduces this risk, even with increasing PD wire passages.