Mini percutaneous nephrolithotomy versus standard percutaneous nephrolithotomy for the management of renal stones over 2 cm: a systematic review and meta-analysis of randomized controlled trials

INTRODUCTION: Standard percutaneous nephrolithotomy (sPCNL) is recommended for renal stones over 2 cm. Mini percutaneous nephrolithotomy (mPCNL) has also emerged as a promising technique in this setting. We performed a systematic review and meta-analysis of randomized controlled trials (RCTs) comparing the safety and efficacy of sPCNL to mPCNL for the management of renal stones over 2cm.EVIDENCE ACQUISITION: We systematically searched PubMed, Cochrane Library and Scopus databases until April 2021 and sources of grey literature for relevant RCTs. We performed a meta-analysis of odds ratios (ORs) to compare bleeding or other complications and stone-free rate (SFR) between sPCNL and mPCNL. Similarly, we undertook a meta-analysis of weighted mean differences for the mean operative and hospitalization time between the two techniques (PROSPERO: CRD42021241860).EVIDENCE SYNTHESIS: Pooled data from 8 RCTs (2535 patients) were available for analysis. sPCNL was associated with a higher hemoglobin drop (0.59 g/dL, 95%CI: 0.4-0.77, I2=93%), higher likelihood of postoperative blood transfusion (OR: 2.58, 95%CI: 1.03-6.45, I2=30%) and longer hospital stay (0.75 days, 95%CI: 0.45-1.05, I2=73%) compared to mPCNL. No significant differences were demonstrated in SFR (OR: 0.92, 95%CI: 0.74-1.16, I2=0%) and mean operative time (4.05 minutes, 95%CI: -9.45-1.37, I2=91%) after sPCNL versus mPCNL. Similarly, no significant differences were observed for postoperative fever, pain and Clavien-Dindo complications.CONCLUSIONS: mPCNL represents a safe and effective technique and may be also recommended as a first-line treatment modality for well-selected patients with renal stones over 2cm. Still, further high-quality RCTs on the field are mandatory since the overall level of evidence is low.