This study aimed to investigate risk factors for urinary infection in patients with negative preoperative urine culture after percutaneous nephrolithotomy (PCNL) and to develop a predictive model to assist clinicians in preoperative assessment of infection risk.

278 patients with negative preoperative urine cultures who underwent PCNL in our hospital from January 2020 to December 2023 were included. Clinical data, including age, sex, body mass index (BMI), diabetes, hypertension, stone characteristics, hydronephrosis, and intraoperative parameters were collected. Multivariate logistic regression analysis was performed to identify independent risk factors for postoperative urinary infection. A predictive model was subsequently constructed based on these factors.

The incidence of postoperative urinary infection was 11.9% (33/278). Univariate analysis revealed that female sex, larger stone burden, hydronephrosis, and positive urine white blood cells (WBCs) were significantly associated with postoperative urinary infection (P<0.05). Multivariate analysis identified stone burden≥500 m² (OR=3.07, P=0.035), hydronephrosis (OR=1.34, P=0.034), and positive urine WBCs (OR=31.50, P<0.001) as independent risk factors for postoperative urinary infection. The predictive model demonstrated excellent discriminatory performance, with an area under the receiver operating characteristic (ROC) curve (AUC) of 0.89.

Patients with negative preoperative urine culture remain at risk of postoperative infection following PCNL, particularly those with larger stone burden, hydronephrosis, or positive urine WBCs. The predictive model provides clinicians with a practical tool for preoperative infection risk stratification.