Abstract
BACKGROUND: Periampullary diverticulum (PAD) is a common anatomical variant, but its association with post-endoscopic retrograde cholangiopancreatography (ERCP) pancreatitis (PEP) remains controversial. While PAD may alter ampullary anatomy, increasing technical difficulty during ERCP, existing studies report inconsistent findings on its role in PEP pathogenesis. We hypothesize that PAD presence, particularly type B, shows a significant association with PEP development and may interact with procedural factors like pancreatic duct guidewire insertion. AIM: To examine the association between PAD (including subtypes A/B) and PEP incidence after ERCP for choledocholithiasis. METHODS: We conducted a retrospective cohort study of 615 patients undergoing ERCP at two tertiary hospitals from 2023 to 2025. Participants were stratified into PAD (n = 183; subtype A = 125, subtype B = 58) and non-PAD (n = 432) groups. The primary outcome was PEP incidence. Multivariable logistic regression adjusted for age, sex, hypertension, diabetes, gallbladder surgery, and guidewire insertion. Statistical significance was set at P < 0.05 (two-tailed). RESULTS: PAD prevalence was 29.8% (183/615). PEP occurrence was more frequent in PAD patients [15.3% (28/183)] than in non-PAD patients [4.2% (18/432)], odds ratio (OR) = 3.86, 95% confidence interval: 2.03-7.35, P < 0.001. Type B PAD showed a stronger association with PEP than type A (OR = 14.16, 95% confidence interval: 5.84-34.34, P < 0.001). Guidewire pancreatic duct entry was linked to higher PEP odds in PAD patients (adjusted OR = 5.02, P < 0.05). Hypertension also demonstrated an association with PEP in the PAD subgroup (P = 0.012). CONCLUSION: PAD, particularly type B, is independently associated with PEP after ERCP. Patients with these features, especially those with hypertension or pancreatic duct instrumentation, may benefit from enhanced monitoring and prophylaxis.