Post-endoscopic retrograde cholangiopancreatography pancreatitis (PEP) remains the most common adverse event associated with ERCP and is particularly frequent in high-risk patients. Unintentional guidewire insertion into the pancreatic duct is recognized as a major procedure-related risk factor for PEP. Although prophylactic pancreatic stent (PPS) placement has been shown to reduce the incidence of PEP, identifying appropriate candidates before ERCP is often difficult, and unnecessary PPS insertion may introduce technical challenges or stent-related complications. Since January 2017, our institution has performed immediate insertion of a 4-Fr PPS in patients who experienced unintentional pancreatic duct guidewire insertion. The present study aimed to evaluate the effectiveness of this selective PPS strategy.

This retrospective single-center cohort study included consecutive patients who underwent ERCP for biliary indications between January 2015 and December 2023. Eligible patients had intact papillae and experienced unintentional pancreatic duct guidewire insertion during the procedure. Patients with surgically altered anatomy, acute pancreatitis, main pancreatic duct obstruction, or intraductal papillary mucinous neoplasm were excluded.

At our institution, immediate placement of a prophylactic pancreatic stent is actively attempted whenever possible in patients with unintentional pancreatic duct guidewire insertion.

Accordingly, patients were categorized into two groups based on whether a stent was actually placed. The PPS group consisted of patients in whom a 4-Fr, 3-cm pigtail pancreatic stent (Advanix™, Boston Scientific) was successfully inserted immediately after biliary cannulation, whereas the non-PPS group consisted of patients in whom PPS placement was not performed despite unintentional pancreatic duct guidewire insertion.

The primary endpoint was the incidence of post-ERCP pancreatitis (PEP). Secondary endpoints included PEP severity, serum amylase concentrations measured the day after ERCP, ERCP-related adverse events, and identification of independent risk factors for PEP using multivariate logistic regression analysis. PEP and its severity were defined according to established consensus criteria.

Of the 2,930 ERCP procedures performed during the study period, 366 patients met the eligibility criteria and were included in the final analysis (PPS group, n = 206; non-PPS group, n = 160). Although no major differences were observed in baseline characteristics, the frequencies of endoscopic sphincterotomy (EST), endoscopic biliary drainage (EBD), and biliary biopsy were higher in the PPS group. In contrast, there were no significant differences between the groups in the time required to achieve successful biliary cannulation or in the total procedure time.

Serum amylase levels measured on the day after ERCP were significantly lower in the PPS group. The incidence of post-ERCP pancreatitis was significantly lower in the PPS group than in the non-PPS group (14.8% vs. 29.4%, p < 0.001). The incidence of moderate or severe PEP was also significantly reduced in the PPS group (3.4% vs. 10.6%, p = 0.009).

Furthermore, univariate and multivariate logistic regression analyses demonstrated that PPS insertion (p = 0.008) and a history of cholangitis (p = 0.008) were independent protective factors associated with a reduced risk of PEP.

Immediate insertion of a 4-Fr prophylactic pancreatic stent following unintentional pancreatic duct guidewire insertion significantly reduced both the incidence and severity of PEP. This selective strategy demonstrated a high technical success rate and was not associated with increased procedure time or additional adverse events. These findings indicate that selective prophylactic pancreatic stenting may be a practical and effective approach to reducing the risk of PEP in patients who experience unintentional pancreatic duct guidewire insertion during ERCP.