Early positive drain cultures predict major morbidity independent of postoperative pancreatic fistula formation after pancreatoduodenectomy

Background Early postoperative drain cultures are associated with intra-abdominal infectious complications after pancreatoduodenectomy (PD), but their value for predicting overall major morbidity and complementing conventional postoperative pancreatic fistula (POPF)-based risk stratification remains unclear. Therefore, this study evaluated the association between early postoperative drain culture positivity (Culture+) and major morbidity and assessed its utility for postoperative risk stratification following PD. Methods We retrospectively reviewed 449 consecutive patients who underwent PD with surveillance drain cultures obtained within postoperative day (POD) 3 between 2016 and 2025. The primary endpoint was major morbidity (Clavien–Dindo grade IIIa or higher). Independent predictors were identified using multivariable logistic regression, followed by a subgroup analysis in patients with POD3 drain amylase (D3DA) levels <500 U/L. Results Sixty-two patients (13.8%) were categorized as Culture+. Major morbidity occurred significantly more frequently in patients with Culture + than in those with Culture– (33.9% vs. 14.7%, p = 0.0002). Multivariable analysis identified D3DA ≥500 U/L (odds ratio [OR] 2.27, 95% confidence interval [CI] 1.31–3.92, p = 0.004) and Culture+ (OR 3.04, 95%CI 1.59–5.74, p = 0.0009) as independently associated with major morbidity. Among patients with D3DA <500 U/L, Culture + remained significantly associated with increased risk of major morbidity. Conclusion Early postoperative drain culture positivity is an independent predictor of major morbidity after PD. Patients with positive drain cultures remain at increased risk of major morbidity even when drain amylase levels are low, suggesting that surveillance drain cultures may provide clinically useful information for postoperative risk stratification.