Stone at the same location for 2 months predicts impacted stones and stone‐free status after shock wave lithotripsy for ureteral stones: A Funabashi clinic expert study
Objectives
To evaluate the success rate of shock wave lithotripsy and identify predictors of stone‐free status after shock wave lithotripsy for ureteral stones, focusing on the impact of stones remaining in the same location for 2 months (SSL2).
Methods
A retrospective analysis was conducted on 501 patients with ureteral stones treated with shock wave lithotripsy by expert surgeons (each with over 1000 shock wave lithotripsy operations) at a single Japanese institution in 2020. Logistic regression analysis identified predictors of stone‐free status, including stone length, skin‐to‐stone distance, stone density (Hounsfield Unit), Hounsfield Unit above/below the stone, stone position, and duration of stone at the same location (SSL2).
Results
Ninety patients were excluded, resulting in 411 patients undergoing an average of 1.15 ± 0.4 sessions (range: 1–4). 344 patients (83.7%) achieved stone‐free status after a single session. The overall 1‐month stone‐free rate was 71.4%, and the 3‐month stone‐free rate was 88.8%. Stone at the same location ≥2 months (SSL2) was an independent predictor of 1‐month stone‐free status (odds ratio = 2.25, 95%CI: 1.10–4.57, p = 0.025), while mean stone density ≥ 813 HU was an independent predictor of 3‐month stone‐free status (odds ratio = 2.66, 95% CI: 1.10–6.45, p = 0.03).
Conclusion
Stone at the same location ≥2 months (SSL2) was a potent predictor of 1‐month and 3‐month stone‐free status. This condition is associated with impacted stones and can aid in decision‐making for shock wave lithotripsy treatment selection.
