To compare the safety and efficiency of minimally invasive percutaneous nephrolithotomy (mini-PCNL) with standard-PCNL for the management of 20-40 mm size kidney stones.
A multi-center randomized controlled trial (RCT) was started from January 1st 2016. There are 30 centers participating in this study and competitive case enrollment was carried out. The access sheath size for mini-PCNL was 18Fr, while standard-PCNL was 24Fr.
Till now, totally 316 cases were enrolled and 20 cases were quitted due to pus appearance or severe hemorrhage when puncture. 297 PCNL procedures were performed for renal stones 20-40mm in diameter. Among the treatments, 146 cases were mini-PCNLs, while 151 cases were standard-PCNLs. The average stone size in mini-PCNL group was 30.83±7.12mm, and 29.6±7.44mm in standard-PCNL group. S.T.O.N.E score for mini-PCNL and standard-PCNL were 6.96±1.16 and 7±1.19, respectively. There was no statistical difference in terms of operative time and hematocrit drop between mini-PCNL and standard-PCNL (42.1±24.3 vs 41.2±21.3 min, 8.82±7.9 vs 9.72±7.73%). The stone free rate (SFR) at 1 day postoperatively of mini-PCNL was similar to that of standard-PCNL (79.3% vs 78.1%). Mini-PCNL has an advantage over standard-PCNL in terms of tubeless (including total tubeless) rate (84.2% vs 21.3%). Although there were no statistical difference in terms of visual analogue scale (VAS) score, patient felt more comfortable in the mini-PCNL group according to Bruggman comfort score (BCS) at 24h postoperatively (3.3±0.8 vs 2.7±0.9). Hospitalization for the mini-PCNL group was shorter than that required by the standard-PCNL group (6.3±2.2 vs 8.5±3.5 days). Analgesics were required more frequently for standard-PCNL postoperatively than mini-PCNL (45% vs 35%). All the complications were Clavien I or Clavien II according to Clavien grade system. The complication rate of mini-PCNL had no significant difference with that of standard-PCNL (51.5% vs 58.5%). No statistical difference was recorded in terms of postoperative fever (≥38℃) between two groups (19.8% vs 17.1%). No transfusion was required in both group.
Mini-PCNL could be a safe and effective approach for the treatment of 20-40mm kidney stones. Although the access tract size of mini-PCNL is smaller, it has a similar SFR to standard-PCNL. Moreover, the infectious complication of mini-PCNL, such as postoperative fever, would not increase. Mini-PCNL has advantages on tubeless rate, hospital stay and BCS score.