Extraction-string ureteral stents and postoperative infection after flexible ureteroscopy: an IPTW-adjusted analysis.

Extraction-string ureteral stents facilitate non-cystoscopic removal after ureteroscopy, but concerns remain regarding postoperative infection and accidental dislodgement. We evaluated whether extraction-string stents were associated with postoperative infection after flexible ureteroscopic lithotripsy (fURSL) in a cohort restricted to procedures with the distal Double-J (D-J) stent portion positioned within the bladder. This retrospective observational study included 102 procedures in 92 unique patients: 58 extraction-string and 44 conventional non-string procedures. Postoperative infection was defined as fever > 38 °C or a positive postoperative urine culture during the stent-indwelling period. Propensity scores incorporated age, sex, positive preoperative urine culture, preoperative pyuria, and procedure laterality. Stabilized inverse probability of treatment weights were truncated at the 1st and 99th percentiles; effective sample size was 85.38. Crude postoperative infection occurred in 8/58 (13.8%) extraction-string and 6/44 (13.6%) non-string procedures. After weighting, estimated infection rates were 13.6% and 8.8%, respectively (OR 1.64, 95% CI 0.50-5.44; P = 0.416). Fever, positive postoperative urine culture, postoperative pyuria, and postoperative day 1 pain did not differ significantly. Sensitivity analyses accounting for repeated procedures and propensity-model specification were consistent with the primary analysis. Extraction-string stent use was not significantly associated with postoperative infection after fURSL; however, the limited number of events and wide confidence intervals preclude exclusion of a clinically meaningful difference.