Objective:To investigate the risk factors for postoperative abdominal infection following pancreaticoduodenectomy (PD).MethodsThe clinical data of 285 patients who underwent PD in Nanjing Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medical School from January 2018 and March 2021 was collected and analyzed retrospectively. Patients were divided into infection group and non-infection group based on the occurrence of abdominal infection. Observed parameters included: (1) Comparison of perioperative indicators and postoperative complications between the two groups; (2) analysis of risk factors for abdominal infection after PD; (3) distribution of bacterial strains isolated from patients' drain samples. Continuous variables were compared using independent-samples t-test and described as mean ± standard deviation (SD) when the data showed normal distribution. Mann-Whitney U test was used and expressed as median (interquartile range) (IQR) when they were not normally distributed. Categorical variables were compared using Chi-squared test or Fisher's exact test as appropriated, expressed as absolute number and percentage. Multivariate analysis was conducted by Logistic regression model.Results(1) Comparison of perioperative variables and postoperative complications between the two groups: 84 (29.5%) patients occurred abdominal infection after PD. The ratio of preoperative biliary drainage, preoperative total bilirubin, operation time, diameter of main pancreatic duct, the rate of clinically relevant postoperative pancreatic fistula, biliary leakage, post-pancreatectomy hemorrhage, major complication (Clavien-Dindo grade≥Ⅲ) were significantly higher in the abdominal infection group (P<0.05). (2) Analysis of risk factors of abdominal infection after PD: preoperative biliary drainage (OR=3.143, 95% CI 1.610-6.136), operation time (OR=2.215, 95% CI 1.170-4.196), clinically relevant postoperative pancreatic fistula (OR=13.723, 95% CI 7.034-26.774) and biliary leakage (OR=8.164, 95% CI 2.414-27.605) were independent risk factors for abdominal infection after PD (all P<0.05). (3) distribution of bacterial strains isolated from PD patients'drain samples: the most common bacterial species isolated were Klebsiella pneumoniae, followed by Enterococcus faecium, Staphylococcus epidermidis, Enterococcus faecium.ConclusionPreoperative biliary drainage, operation time, clinically relevant postoperative pancreatic fistula and biliary leakage were independent risk factors for abdominal infection after PD.