Prone versus modified supine position in percutaneous nephrolithotomy: a prospective randomized study.

Objective: To perform a prospective randomized trial comparing the efficacy and safety of percutaneous nephrolithotomy (PCNL) in the prone and modified supine positions. Methods: Between August 2010 and August 2011, 102 patients with renal calculi and 20 patients with ureteral calculi were randomized to undergo fluoroscopy and ultrasound-guided PCNL procedures in the prone or modified supine position. Baseline characteristics, puncture position, numbers of punctures, operation time, stone free rate, loss of blood, hospital stay and second phase PCNL were compared in the two groups. Results: There were no significant differences in gender, age, body mass index, stone location, stone size and the presence of hydronephrosis between the two groups. The rate of second PCNL was significantly higher and the stone clearance rate was significantly lower in the modified supine than in the prone position group. Mean operation time was significantly lower in the prone than in the modified supine position group (78 min vs 88 min, P<0.05). There were no significant differences in rates of rib and calyx puncture, numbers of punctures, mean blood loss, and mean hospital stay between the two groups. Conclusions: Both the prone and modified supine positions are effective and safe for PCNL. Operation time was longer in the modified supine group, and patients undergoing PCNL in the modified supine position more frequently required a second operation due to a lower stone clearance rate.