Perioperative Outcomes of Vacuum-Assisted Versus Standard Mini-Percutaneous Nephrolithotomy: A Propensity Score Overlap Weighting Analysis

Background Vacuum-assisted mini-percutaneous nephrolithotomy (mini-PCNL) improves stone fragment evacuation and surgical efficiency. However, comparative evidence remains limited and susceptible to selection bias. We compared perioperative outcomes of standard and vacuum-assisted mini-PCNL using propensity score overlap weighting. Methods This retrospective study included 80 patients undergoing mini-PCNL between January 2022 and December 2025. Forty patients underwent standard mini-PCNL and 40 underwent vacuum-assisted mini-PCNL. Propensity score overlap weighting was performed using demographic and stone-related characteristics, including age, sex, ASA score, comorbidity status, stone size, stone multiplicity, and Guy's Stone Score. Stone-free status was assessed on postoperative non-contrast computed tomography (NCCT) with 3-mm slice thickness and classified as Grade A (no residual fragments), Grade B (residual fragments ≤2 mm), and Grade C (residual fragments 2.1-4 mm). Perioperative outcomes were compared using weighted regression models. Results After overlap weighting, excellent covariate balance was achieved across baseline variables. Vacuum-assisted mini-PCNL was associated with shorter operative time (53.8 ± 10.9 vs. 74.1 ± 3.8 min, p<0.001), shorter laser fragmentation time (p<0.001), shorter stone extraction time (p<0.001), lower postoperative hemoglobin decrease (p=0.041), reduced estimated blood loss (p=0.043), and shorter hospital stay (p=0.023). Needle puncture and fluoroscopy times were comparable between groups (p=0.540 and p=0.844, respectively). Grade A stone-free status was achieved in 32/40 (80.0%) patients in the vacuum-assisted group and 27/40 (67.5%) in the standard group, whereas Grade B status was observed in 3/40 (7.5%) and 2/40 (5.0%), respectively, and Grade C status in one patient (2.5%) in each group. Although Grade A stone-free status and postoperative complication rates favored the vacuum-assisted group, these differences were not statistically significant. Regression analysis confirmed an independent reduction in operative time (β = -20.28, 95% CI -24.60 to -15.96; p<0.001) and postoperative hemoglobin decrease (β = 2.39, 95% CI 0.10-4.67; p=0.041). Conclusions After propensity score overlap weighting, vacuum-assisted mini-PCNL demonstrated superior operative efficiency and reduced perioperative morbidity compared with standard mini-PCNL. NCCT-based stone-free assessment demonstrated a higher Grade A stone-free rate in the vacuum-assisted group, although this difference was not statistically significant. Larger prospective multicenter studies are warranted to validate these findings.