Is the Supine Position Suitable for Ultrasound-Guided Percutaneous Nephrolithotomy in Patients with Complex Renal Stones?

Introduction: The aim of the study was to assess the safety and efficacy of ultrasound (US)-guided percutaneous nephrolithotomy (PCNL) for complex renal stones when performed in a modified supine position. Methods: We retrospectively reviewed the charts of patients who underwent PCNL for complex renal stones at our institution between August 2018 and December 2021. During this time, 188 consecutive patients underwent US-guided PCNL in the prone position (P group, n = 129) or in the flank-free modified supine position (S group, n = 59). Patient demographics and intraoperative and postoperative data were analyzed. Results: Successful renal access was achieved in all patients. The baseline demographics were comparable between the two groups. The numbers of renal access were significantly higher (2.1 ± 0.4 vs. 1.2 ± 0.2, p = 0.002), and the operation time was comparable (79.1 ± 14.6 min vs. 96.2 ± 19.6 min, p = 0.06) between the two groups. The postoperative hospital stay was also shorter in the P group (6.2 ± 1.5 d vs. 10.2 ± 1.7 d, p = 0.008). The postoperative hemoglobin loss was similar between the P and S groups (1.7 ± 0.4 g/dL vs. 1.8 ± 0.3 g/dL, p = 0.12). The stone-free rate was significantly lower in the S group (57.5% vs. 82.7%, p < 0.001). There were no embolization or septic complications. Twelve patients (20.3%) in the S group underwent simultaneous or staged retrograde flexible ureteroscopy to remove residual stones. Conclusion: US-guided PCNL in the modified supine position was a safe treatment for complex renal stones. However, the single-session stone clearance rate was not ideal. The supine flank-free position may be unsuitable for US-guided PCNL in patients with complex renal stones according to our preliminary findings.