Supine versus prone position in percutaneous nephrolithotomy for kidney calculi: a meta-analysis

Supine position and prone position were the choice for percutaneous nephrolithotomy (PCNL). However, there is still no consensus on the optimal position for PCNL. A systematic literature review was performed, searching Pubmed, Embase, CENTRAL and reference lists for relevant studies. Data from all selected articles were extracted independently by two reviewers and analyzed by RevMan 5 software. Four comparative studies involving 389 cases and 27 case series studies including 1,469 renal units of supine position and 4,837 renal units of prone position were identified. With reference to comparative studies, the mean stone length and the proportions of staghorn and multiple stones were comparable between two positions. There was no significant difference in terms of stone-free rate (risk ratio = 1.00, 95% confidence interval: 0.92 to 1.09; 82.4 vs. 82.1%) and bleeding. The rate of colonic injury in supine PCNL was approximate 0.5% and incidence of pleural injury of 0% was noted for both positions. Pelvic perforation and failed access were comparable between supine and prone position. The operative times of supine position significantly decreased (65 +/- 15 vs. 90 +/- 15 min; mean difference = -24.76, 95% confidence interval: -39.36 to -10.15), but no significant difference was found in mean days hospital stay. Analysis based on the case series showed larger proportion of staghorn and multiple calculi in prone position (45.8 vs. 31.7%), the supine PCNL had slightly lower bleeding and similar stone-free rate compared with the prone position. For general patients with kidney calculi, PCNL in supine position has similar stone-free rate compared with prone. Supine PCNL do not increase related complications. The operative times significantly decrease in supine position.