Supine Versus Prone Position in Percutaneous Nephrolithotomy for Kidney Calculi: A Meta-Analysis

There are several positions in the operation of percutaneous nephrolithotomy (PCNL), such as prone position, supine position, flank position, and modified supine position for PCNL, but the supine and prone positions are the main two choices for several years. However, there is still discrepancy on the optimal position for PCNL. Therefore, we performed this meta-analysis to evaluate safety and efficacy of the supine versus the prone position in PCNL for renal calculi.

We searched MEDLINE, SCOPUS, and the Cochrane database libraries to look for relevant studies. All eligible controlled trials comparing supine versus prone positions for treating renal calculi were included in the meta-analysis. The main outcome of efficacy (stone-free rate, mean operative time, and hospitalization time) and safety (complication, blood transfusions) were assessed by using Review Manager 4.2 software. We calculated the estimate of effect associated with the two positions according to the heterogeneity using random-effects or fixed-effects models.

Thirteen studies (six randomized controlled trials and seven retrospective studies) with a total of 6881 patients contributed to this meta-analysis. The meta-analysis indicated/suggested that PCNL in the prone position was associated with a higher rate of stone clearance than PCNL in the supine position (odds ratio [OR]: 0.74; 95% confidence interval [CI]: 0.65, 0.84; p < 0.00001). A shorter mean operative time was observed in the supine groups (weighted mean difference [WMD]: -18.27; 95% CI: -35.77, -0.77; p = 0.04). Compared with the prone position, there was also a lower incidence of blood transfusions in the supine groups (WMD: 0.73; 95% CI: 0.56, 0.95; p = 0.02). No difference was observed between the positions with regard to the hospital stay (WMD: -0.14; 95% CI: -0.76, 0.47; p = 0.65) and complications (OR: 0.88; 95% CI: 0.76, 1.02; p = 0.10).

Compared with the prone position, the PCNL in the supine position has a slightly lower rate of stone clearance, albeit shorter mean operative time, and lower incidence of blood transfusions. The meta-analysis suggests that the PCNL in the supine position is a promising alternative.