Post-Percutaneous Biliary Drainage Pancreatitis: Initial Transpapillary Passage as a High-Risk Procedural Phase.

PURPOSE: To determine whether the initial transpapillary passage is associated with an increased risk of post-percutaneous biliary drainage pancreatitis (PBDP) compared with subsequent procedures through previously instrumented papillae. MATERIALS AND METHODS: A retrospective observational study of consecutive percutaneous biliary procedures performed between December 2020 and July 2025. Procedures were classified as primary or secondary according to papillary status. The primary outcome was PBDP, defined according to the revised Atlanta classification. Complementary adjusted and sensitivity analyses were performed to assess robustness. RESULTS: A total of 312 procedures in 153 patients were analyzed, including 260 transpapillary procedures (122 primary and 138 secondary). PBDP occurred in 26 of 260 procedures (10.0%), including 23 of 122 primary procedures (18.9%) and 3 of 138 secondary procedures (2.2%) (P < 0.001). In the prespecified adjusted analysis using Firth penalized logistic regression, primary procedure remained associated with PBDP (adjusted OR, 10.00; 95% CI, 3.49-38.69; P < 0.001). All moderate-to-severe pancreatitis (6/122 vs 0/138), ICU admissions (5/122 vs 0/138), and pancreatitis-attributable deaths (4/122 vs 0/138) occurred after primary procedures. Patient-level sensitivity analysis showed a similar direction of effect (P = 0.369). CONCLUSION: PBDP occurred predominantly during the initial transpapillary passage, with all moderate-to-severe pancreatitis, ICU admissions, and pancreatitis-attributable deaths occurring during this procedural phase. These findings identify the initial transpapillary passage as a distinct high-risk procedural phase and support future studies evaluating targeted preventive interventions.