Comparison of stone-free rate, operative parameters, and complication rate according to Guy’s stone score in supine versus prone percutaneous nephrolithotomy: A prospective observational study

Background: The term supine percutaneous nephrolithotomy (PCNL) has emerged as a viable alternative to the traditional prone approach. Supine positioning offers several theoretical advantages, including improved anesthetic safety, reduced operative time, and the ability to perform simultaneous antegrade and retrograde procedures without repositioning. However, comparative evidence regarding outcomes between supine and prone PCNL remains limited, particularly when stratified by stone complexity using Guy’s stone score (GSS). Aims and Objectives: The study was conducted to compare stone-free rates (SFRs), operative parameters, and complication rates between supine and prone PCNL techniques, with outcomes stratified according to GSS complexity. The secondary objective was to evaluate the impact of stone complexity on surgical outcomes in both positioning techniques. Materials and Methods: This prospective observational study was conducted at the Department of Urology, R.G. Kar Medical College and Hospital, Kolkata, from August 2023 to February 2025. A total of 100 patients undergoing PCNL were randomly allocated to supine (n=50) or prone (n=50) groups. Outcomes included operative time, blood loss, complication rates according to Clavien-Dindo classification, and SFR, stratified by GSS. Statistical analysis was performed using SPSS version 25.0 with an independent t-test for continuous variables and a chi-square test for categorical variables. Results: Of a total of 100 patients, 50% underwent supine PCNL while 50% underwent prone PCNL, with mean ages of 45.44±14.51 and 51.54±12.32 years, respectively. Supine PCNL demonstrated significantly shorter gross operative time (97.8±31.17 versus 128.8±35.51 minutes, p<0.001), total operative time (82.4±29.73 versus 104.4±31.84 minutes, p<0.001), and fragmentation time (27.22±17.80 versus 40.04±21.30 minutes, p<0.001). Estimated blood loss was significantly lower in the supine group (274±152.28 versus 400±170.83 mL, p<0.001). Severe complications (Clavien grade ≥III) occurred in 8% of supine versus 36% of prone patients (p=0.003). SFRs were comparable (92% versus 88%, p=0.11). Higher GSS correlated with increased complications, longer operative time, and decreased SFR in both groups. Conclusion: Supine PCNL demonstrated significant advantages over prone PCNL in terms of operative efficiency and safety profile while maintaining comparable stone clearance rates. The technique offers reduced surgical morbidity, particularly in patients with lower stone complexity scores as assessed by GSS.