Comparison of Prone and Supine Positions for Suction Mini Percutaneous Nephrolithotomy (PCNL) for Kidney Stone Disease. Results from a Prospective Multicenter Series from the Endourology Section of the European Association of Urology and the Suction Mini-PCNL Collaborative Study Group

Abstract

Background and objective: The optimal patient position for percutaneous nephrolithotomy (PCNL) remains a matter of debate. Our aim was to evaluate the association between prone versus supine positioning and perioperative and postoperative outcomes of suction mini-PCNL. Methods: In this prospective multicenter observational study, we analyzed data for 1534 patients treated in 30 centers between March and November 2024. Outcomes included the stone-free rate (SFR) assessed via 30-d computed tomography, and complication rates. Multivariable analysis was used to assess the effect of prone positioning on stone-free status (zero fragments) and overall complications, with adjustment for other covariates. Key findings and limitations: There were 653 patients (43%) in the prone group and 881 (57%) in the supine group. Patient demographics were similar between the groups, except for body mass index. In terms of Guy's stone score, the prone group had a higher proportion of score 1 stones (60% vs 47%) and the supine group a higher proportion of score 4 stones (6.9% vs 3.2%). Median stone volume did not differ significantly, at 1636 mm³ in the supine group and 1725 mm³ in the prone group (p = 0.7). The prone group had more frequent use of spinal anesthesia (68% vs 29%; p < 0.001), fluoroscopy-only guidance (86% vs 61%; p < 0.001), and supracostal access (36% vs 22%; p < 0.001). Surgical time, pain scores, hospital length of stay, and readmission rates were similar between the groups. Zero-fragment stone-free rates were comparable (85% prone vs 81% supine; p = 0.052). Prone position was associated with higher rates of blood transfusion (2.8% vs 0%; p < 0.001), renal pelvic perforation (2.8% vs 0.23%; p < 0.001), and pneumothorax (1.5% vs 0%; p < 0.001). Multivariable analysis revealed that prone positioning was not significantly associated with grade A stone-free status (odds ratio 0.92, 95% confidence interval [CI] 0.66–1.29; p = 0.6) or the overall complication rate (odd ratio 0.87, 95% CI 0.59–1.28; p = 0.5). The nonrandomized study design may have introduced selection bias and limited our ability to establish causal relationships between variables. Conclusions and clinical implications: Both prone and supine positioning for PCNL achieved excellent SFRs with acceptable safety profiles.