Stone Clearance Rates Following Extracorporeal Shock Wave Lithotripsy: Comparative Efficacy in Lower Pole and Other Renal Locations: A Prospective Observational Study.

Abstract

Introduction: Extracorporeal shock wave lithotripsy (ESWL) remains a widely used non-invasive treatment for renal calculi, yet stone clearance in lower pole stones has been debated due to anatomical and gravitational factors. Methods: A prospective observational study was conducted at the Sindh Institute of Urology and Transplantation (SIUT), Karachi, between June and December 2022. A total of 105 patients with solitary renal stones measuring 4–20 mm was included. Patients were categorized by stone location: lower pole (Group 1), mid pole (Group 2), pelvis (Group 3), and upper pole (Group 4). All underwent ESWL on a Storz Modulith SLX lithotripter under a standardized protocol, with a maximum of three sessions. Stone-free status was assessed radiologically three weeks after treatment. Statistical analyses included chi-square and t-tests, with significance at p < 0.05. Results: The mean age of participants was 41.45 ± 12.32 years; 55.2% were male. The mean stone size was 12.3 ± 3.3 mm. The overall stone-free rate was 86.7%. Clearance was achieved in 85.7% of lower pole stones (Group 1), 84.6% in mid pole (Group 2), 87.2% in pelvis (Group 3), and 90.9% in upper pole (Group 4), with no statistically significant differences among groups (p = 0.967). Complications were minimal and self‑limited. Conclusion: ESWL achieved high short-term stone clearance rates across different intrarenal stone locations, with comparable outcomes observed between lower pole and non-lower pole calculi in this cohort. Larger multicenter studies incorporating anatomical and radiological predictors with longer follow-up are needed to validate these findings and optimize patient selection.