Objective: To review and perform a meta-analysis of the available literature on the minimally invasive percutaneous nephrolithotomy (PCNL) techniques in comparison with standard PCNL and retrograde intrarenal surgery (RIRS).

Material and Method: We systematically reviewed PubMed and Galileo in April 2016 to identify all relevant studies between 2010 to April 2016. The stone free rate, operative time, length of stay and blood loss were compared between standard PCNL, mini-PCNL, ultra-mini PCNL, micro-PCNL and RIRS to determine the best modalities for stone treatment.

Results: Included in analysis were 32 studies in a total of 4,586 total cases (316 standard PCNL cases, 2,581 mini PCNL cases, 185 ultra-mini PCNL cases, 316 micro PCNL cases and 739 RIRS cases). The meta-analysis results between standard PCNL vs. mini-PCNL vs. ultra-mini PCNL vs. micro-PCNL vs. RIRS are as follow: 1) mean stone sizes were 29.63, 30.38, 16.04, 13.83 and 14.4, respectively 2) stone free rates (%) were 75.63, 84.88, 86.13, 88.03 and 80.31, respectively 3) operative times (minutes) were 77.46, 57.28, 76.08, 56.53 and 64.39, respectively 4) length of hospital stays (hours) were 165.76, 101.54, 54.73, 45.28 and 32.59, respectively 5) hemoglobin decrease rates (g/L) were 12.87, 9.85, 7.35, 8.91 and 9.38, respectively.

Conclusion: Minimally invasive PCNL have higher stone free rates in comparison to standard PCNL and RIRS. Among the minimally invasive PCNL, mini-PCNL have the greatest flexibility in stone size ranges with comparable operative time, length of stay and blood loss to the others. For large stones (>2 cm), mini-PCNL are superior to standard PCNL in all variable outcomes. Future well designed multicenter randomized controlled trials are needed to support these findings.

Keywords: Percutaneous nephrolithotomy, Miniperc, Ultra-miniperc, Microperc, Retrograde intrarenal surgery, Flexible ureteroscope, Stone surgery, Systemic review, Meta-analysis