Beyond the sheath: unmasking true predictors of Post-fURS fever through propensitymatched precision.

Aim: Flexible ureteroscopy (fURS) is a prevalent minimally invasive treatment for upper urinary tract stones, but postoperative fever remains a considerable concern. The precise role of ureteral access sheath (UAS) utilization in influencing infectious complications following fURS continues to be debated. This study aimed to comprehensively evaluate the perioperative and postoperative outcomes of fURS, with a specific focus on the influence of UAS utilization. Furthermore, we sought to identify independent predictive factors for the development of postoperative fever after fURS, utilizing a propensity score-matched analysis to mitigate confounding variables and enhance the robustness of our findings.

Methods: This retrospective cohort study analyzed 486 patients undergoing fURS, with propensity score matching (PSM) used to create balanced UAS (n = 150) and non-UAS (n = 150) groups. Perioperative outcomes and predictors of postoperative fever (defined as ≥ 37.5 °C within 48 h) were evaluated using univariate, multivariate logistic regression, and receiver operating characteristic (ROC) curve analyses.

Results: Postoperative fever rates were comparable between UAS and non-UAS groups (12% vs. 9.3%, p = 0.454), although UAS use was associated with significantly longer hospital stays (median 5 vs. 4 days, p = 0.003). Independent predictors of postoperative fever included positive preoperative urine culture [adjusted odds ratio (aOR) 7.535, 95% CI 2.681-21.175, p < 0.001], elevated postoperative C-reactive protein (CRP) (aOR: 1.211, 95% CI 1.093-1.343, p < 0.001), and increased postoperative white blood cell (WBC) count (aOR: 1.200, 95% CI 1.012-1.424, p = 0.036). ROC analysis demonstrated high predictive accuracy for postoperative CRP (AUC: 0.943) and a combined prediction model (AUC: 0.951).

Conclusions: Performing fURS without UAS did not significantly increase the risk of postoperative fever, supporting its safety in carefully selected cases. Monitoring preoperative urine culture results and postoperative CRP and WBC levels are critical for the early prediction and timely intervention of postoperative fever.