Suction in Mini-Percutaneous Nephrolithotomy: A Meta-Analysis from the European Association of Urology Section of Endourology

Vacuum-assisted mini-PCNL cleared stones at nearly twice the rate of conventional sheaths across 14 studies and 2,510 patients

Journal: BJU International | Published: 2025-08-29 | Type: Meta-Analysis, Systematic Review | PMID: 40878469 Authors: Ulabedin et al. (The Royal London Hospital; European Association of Urology Section of Endourology) Funding/COI: Not listed

Summary

This PROSPERO-registered meta-analysis compared vacuum-assisted access sheath (VAAS) mini-percutaneous nephrolithotomy against conventional access sheath (CAS) mPCNL for kidney stone removal. Across 14 comparative studies, VAAS outperformed CAS on nearly every measured outcome: shorter operations, higher stone-free rates, fewer complications, and shorter hospital stays. The blood loss picture was the one place the two approaches looked identical.

Claims

• Stone-free rate: VAAS achieved significantly higher stone clearance — OR 1.92 (95% CI 1.57–2.35; P < 0.001), meaning roughly double the odds of clearing stones
• Operating time: VAAS was 17.45 minutes faster on average (95% CI 13.12–21.79; P < 0.001)
• Postoperative fever: Lower in VAAS — OR 0.45 (95% CI 0.35–0.61; P < 0.001)
• Sepsis: Lower in VAAS — OR 0.45 (95% CI 0.22–0.93; P = 0.03)
• Hospital stay: 0.79 days shorter with VAAS (P = 0.03)
• Transfusion rate: No significant difference — OR 0.78 (95% CI 0.46–1.31; P = 0.3)
• Hemoglobin deficit: No significant difference — 0.00 g/dL (P > 0.9)

Study Quality

The review followed PRISMA guidelines with PROSPERO registration — standard procedure for a credible systematic review. Evidence quality was graded using GRADE, which is appropriate methodology. The pool included both RCTs and observational studies; 2,510 patients across 14 studies is a reasonable aggregate sample for this niche surgical comparison.

The mixed-study-design pool is the main methodological caveat. Observational studies are vulnerable to selection bias — surgeons may preferentially deploy VAAS on easier cases or more favorable anatomy, inflating its apparent benefit. The meta-analysis does not appear to stratify by study design in reporting primary outcomes, which limits how confidently the pooled effect sizes can be interpreted.

Red Flags

• COI and funding not reported — for a surgical-device comparison, this is a significant omission. VAAS equipment is commercially manufactured; undisclosed industry ties to device makers would be material
• Mixed RCT/observational pool — if observational studies dominate the 14 included papers, the impressive OR of 1.92 for stone-free rate could partly reflect case-selection bias rather than device superiority
• No stratification by stone burden or complexity — stone size and complexity are major confounders; a technique that works on 10mm stones may not generalize to staghorn calculi
• Sepsis confidence interval is wide — OR 0.45 with a CI of 0.22–0.93 borders on marginal; a larger RCT could shift this either direction

Strengths

• PROSPERO-registered prospectively, reducing outcome-reporting bias
• PRISMA-compliant methodology
• Large aggregate sample for a specialized surgical technique
• GRADE evidence quality assessment applied
• Covers multiple clinically meaningful endpoints including safety signals (sepsis, fever) not just stone-free rate
• Authors explicitly call for further high-quality RCTs rather than overclaiming

Verdict

A competently assembled meta-analysis on a narrow but genuinely useful surgical question. The signal — VAAS reduces operating time, complications, and hospital stay while improving stone clearance — is consistent across outcomes, which lends it some credibility. The missing funding and COI disclosures are a real problem for a device-comparison paper, and the observational-study contamination prevents firm causal conclusions. Worth noting by urologists, but the call for further high-quality RCTs in the conclusion is the authors themselves acknowledging what this paper can't definitively establish.