Pre-laser intraoperative urine culture provides key microbiological information for postoperative infectious management after flexible ureteroscopy for renal stone disease: a prospective single-surgeon study.

INTRODUCTION

Postoperative infectious complications remain a clinically relevant concern after flexible ureteroscopy (FURS), including in patients with negative preoperative bladder urine cultures (UCs). Microbiological discordance between bladder and upper urinary tract samples may contribute to under-recognition of infectious risk. We assessed the clinical value of systematic intraoperative UCs obtained at predefined stages of FURS.

METHODS

We relied on a prospectively collected dataset of 238 consecutive FURS procedures for renal stone disease conducted by a single experienced surgeon performed (2023-2025). UCs were obtained preoperatively and intraoperatively at standardized time points, including bladder urine at the start of the procedure, renal pelvic urine before laser lithotripsy, and renal pelvic urine after lithotripsy. The primary endpoint was postoperative infectious complications, classified as any infection and severe infection (sepsis/septic shock according to international definitions). Associations between culture-positivity patterns and outcomes were evaluated using Fisher's exact test and univariable logistic regression.

RESULTS

Among 952 UCs analyzed, 79% were negative overall. A total of 136 patients (57.1%) had negative cultures at all sampling time points. De novo intraoperative culture positivity occurred in 7.1% of patients with negative preoperative UCs. Pre-laser intraoperative UC positivity was significantly associated with postoperative infectious complications, with rates of any infection and severe infection of 27% and 23%, respectively. In univariable analyses, pre-laser intraoperative positivity (either renal pelvic or bladder urine) was associated with an increased risk of any infection (OR 6.14, 95% CI 1.43-24.3; p = 0.01) and severe infection (OR 8.87, 95% CI 1.53-51.8; p = 0.011) in reference to the all negative UC group. In contrast, isolated preoperative or post-laser UC positivity was not significantly associated with infectious outcomes.

CONCLUSIONS

Intraoperative UCs obtained before laser lithotripsy were significantly associated with postoperative infectious complications following FURS for renal stone disease. Preoperative bladder UCs alone showed limited ability to identify patients at increased infectious risk. As culture results become available 24-48 h after surgery, intraoperative pre-laser sampling may represent a valuable microbiological tool to guide timely, culture-informed antibiotic therapy in patients who develop postoperative infectious complications.