[Efficacy of rigid ureteroscopic laser lithotripsy combined with N-trap in the treatment of ureteral stones with a maximum diameter equal to or greater than 1.5 cm].

Objective: To investigate the efficacy of rigid ureteroscopic laser lithotripsy combined with N-trap (RULL + N-trap), which is scoop-shaped, in the treatment of ureteral stones with a maximum diameter ≥ 1.5 cm.

Methods: This retrospective cohort study included patients diagnosed with ureteral calculi who underwent rigid ureteroscopic lithotripsy (RULL) combined with N-Trap stone entrapment system at the Department of Urology, Peking University Third Hospital, by the same surgical team between June 2021 and September 2024. A total of 364 patients were initially enrolled. After excluding 21 patients due to missing critical outcome variables, two distinct cohorts were established: 38 patients with ureteral stones measuring ≥1.5 cm in maximum diameter, and 305 patients with stones < 1.5 cm in maximum diameter. To minimize selection bias and control for confounding variables, propensity score matching (PSM) was employed. This resulted in two well-balanced groups: 31 patients with stones ≥1.5 cm in maximum diameter and 31 patients with stones < 1.5 cm in maximum diameter, matched on baseline demographic and clinical characteristics. The primary outcomes assessed between the two groups included stone clearance. Secondary outcomes included changes in renal function indicators, specifically serum creatinine (SCr) and estimated glomerular filtration rate (GFR), and other factors like postoperative hospital stay and operative time.

Results: In the matched cohort, the patients with stones ≥1.5 cm in maximum diameter had significantly longer operative time compared with those with smaller stones: (85.8±28.8) min vs. (62.4±24.6) min (P < 0.05). Postoperative length of hospital stay showed no significant difference: (2.26±1.79) d vs. (2.03 ± 0.80) d (P>0.05). The stone clearance on postoperative day one was 90.3% in the study group vs. 100.0% in the control group (P>0.05). One month postoperatively, the stone clearance was 93.5% vs. 100.0%, respectively (P>0.05). Changes in SCr were (-6.58±16.10) μmol/L vs. (-13.70±12.50) μmol/L, and changes in GFR were (5.92±14.90) mL/(min·1.73 m²) vs. (7.47±11.20) mL/(min·1.73 m²), with no statistically significant differences observed between the two groups for either renal function marker (P > 0.05).

Conclusion: Ureteroscopic lithotripsy combined with N-trap is an optional method for treating ureteral stones with a maximum diameter ≥1.5 cm. The overall therapeutic efficacy is comparable, with the added benefit of significantly reducing the economic burden on patients.