Outcomes Following Institutional Adoption of Vacuum-Assisted Micro-ECIRS for Symptomatic 1–2 cm Lower Pole Renal Stones: A Retrospective Non-Concurrent Cohort Study

Background/Objectives: Micro-percutaneous nephrolithotomy (micro-PCNL) offers direct access to lower pole stones but has limited fragment evacuation. Vacuum-assisted micro-endoscopic combined intrarenal surgery (micro-ECIRS) adds flexible ureteroscopy and suction. We evaluated outcomes after institutional adoption of this technique for symptomatic 1–2 cm lower pole stones. Methods: This retrospective non-concurrent cohort included 81 consecutive adults treated between January 2016 and July 2025 (micro-ECIRS, n = 42; micro-PCNL, n = 39). Only micro-PCNL procedures (n = 33) preceded January 2021. One-month low-dose noncontrast computed tomography (earlier, pre-intervention, in four patients) classified outcomes as Grade A (no residual fragment), Grade B (none >2 mm), or Grade C (none >4 mm; main outcome). Comparisons were unadjusted. Results: Grade C was attained in 90.5% (micro-ECIRS) versus 64.1% (micro-PCNL) (absolute difference 26.4 percentage points, 95% confidence interval [CI] 8.2–43.1; risk ratio [RR] 1.41, 95% CI 1.09–1.82; p = 0.007) and Grade B in 71.4% versus 46.2% (p = 0.025). Grade A did not differ significantly (42.9% vs. 28.2%; p = 0.246). Secondary puncture (4.8% vs. 28.2%) and auxiliary procedures (4.8% vs. 25.6%) were less frequent after micro-ECIRS (both p < 0.05). Complications did not differ significantly (11.9% vs. 30.8%; p = 0.055). Conclusions: In this retrospective, predominantly non-concurrent cohort, institutional adoption of vacuum-assisted micro-ECIRS was associated with higher rates of no residual fragment larger than 2 mm or 4 mm and fewer additional punctures and subsequent procedures. A difference in complete stone clearance was not demonstrated. Treatment–era confounding, baseline imbalance, and complete-case selection prevent causal attribution to the technique.