Post written by Georgios Papachristou, MD, PhD, from the Division of Gastroenterology, Hepatology, and Nutrition, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA.

This was a secondary data analysis of the stent versus indomethacin (SVI) trial, a recently completed, National Institutes of Health—funded, multicenter, randomized controlled trial including 20 centers in the United States and Canada.

We specifically looked at 1900 participants in the SVI trial with an intended biliary cannulation attempt. Our primary goal was to elucidate which aspects of a difficult biliary cannulation confer the greatest risk for post-ERCP pancreatitis (PEP), as detailed ERCP reports were completed for each participant.

We were able to provide further insight into the different components of a difficult biliary cannulation. We found that 84.1% of SVI participants had a difficult biliary cannulation, which was defined a priori as ≥6 cannulation attempts or ≥6 minutes spent cannulating. High preprocedural risk for PEP included any of these indications: biliary sphincter of Oddi dysfunction, pancreatic sphincter of Oddi dysfunction, pancreas divisum, or recurrent acute pancreatitis. In addition, participants were considered high risk if they had a clinical suspicion of sphincter of Oddi dysfunction or prior history of PEP or were women <50 years old.

We then created 3 subgroups to try to delineate different levels of risk based on cannulation difficulty and preprocedural risk factors. One subgroup included those with a difficult biliary cannulation and a high preprocedural risk profile for PEP, another subgroup contained those with a difficult biliary cannulation without a high preprocedural risk profile, and the last subgroup involved those with a high preprocedural risk profile but without a difficult cannulation.

In essence, as seen in the figure, the highest risk of PEP was observed in those with a difficult cannulation and a high preprocedural risk profile with a rate of 20.7%. The next highest PEP rate was observed in those with a high preprocedural risk profile without a difficult cannulation at 13.5%. Lastly, the subgroup with a difficult cannulation without a high preprocedural risk profile had a rate of 8.8%.

There are a couple of key findings in addition to the different rates of PEP seen in the 3 subgroups. In terms of intraprocedural factors, the number of wire passages into the pancreatic duct (PD) was significantly associated with PEP, with risk of pancreatitis increasing proportionally with the number of wire passages. Notably, PD contrast injection, performing a sphincterotomy, and the type of IV fluids were not associated with PEP.

Importantly, the combination of rectal indomethacin and prophylactic PD stent placement was associated with a reduced risk of PEP and, when stratifying the rate of PEP by the number of wire passages, the benefit of PD stenting became clearer. Even with just 1 wire passage into the PD, you can see the benefit PD stent placement provides in mitigating the risk of PEP.

Although this study provides further insight into the different components of a difficult biliary cannulation, a great amount of work still needs to be conducted to determine the inflammatory pathway by which PEP propagates. Only then can we perhaps determine other prophylactic therapies that help us lower the rate of PEP closer to 0%.

We also need to figure out how the temporality of events plays a role. For example, if we place a PD stent early in the procedure, is it more protective than placing a PD stent late in the procedure? We need to determine biomarkers for PEP that can be identified preprocedure, so we know who is truly high risk for PEP.

Post-ERCP pancreatitis rates among the 3 groups: difficult cannulation with high preprocedural risk, nondifficult cannulation with high preprocedural risk, and difficult cannulation without high preprocedural risk.

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