The effectiveness and safety between prone position and supine position for ultrasound guided shock wave lithotripsy in proximal ureteral stones: a multi-center prospective propensity score-matching study.

Background: Although shock wave lithotripsy (SWL) has been considered to be effective in treating ureteral stones, a definitive conclusion remains unclear on which patient's position is the optimal option for proximal ureteral stones. The purpose of this study is to assess the ideal position of ultrasound guided SWL for the treatment of proximal ureteral stones.

Methods: This prospective study was conducted in multi-center from June 2020 to December 2023. Patients who underwent SWL in prone or supine position for proximal stones were enrolled in this study. The primary outcome was stone-free rate (SFR); the secondary outcome was complete SFR, sessions of SWL, and complications. Propensity score-matched (PSM) analysis was performed.

Results: Finally, 1187 patients with proximal ureteral stones were enrolled in this study; of which 50.5% (599) were treated with prone position and 49.5% (588) underwent supine position. After 1:1 PSM, the prone position group was superior in SFR (85.7% vs. 77.4%, P = 0.001), and complete SFR (83.3% vs. 75.0%, P = 0.001) compared with the supine potion group. The sessions of SWL (1.27 vs. 1.20, P = 0.092) and complications rate (all P values > 0.05) were comparable between the two groups. In addition, the prone group had shorter skin-to-stone distance (SSD) on ultrasound than the supine group (50 mm vs. 101 mm, P < 0.001).

Conclusion: This multi-center prospective PSM study demonstrated that the prone position could increase the SFR and had comparable safety for ultrasound guided SWL among patients with proximal ureteral stones. Therefore, we advocate its priority application to patients with proximal ureteral stones when the prone position is possible.