Enhanced Effectiveness of Extracorporeal Shock Wave Lithotripsy for Residual Stones Post-percutaneous Nephrolithotomy: A Comparative Study With Primary Stones of Similar Size.

INTRODUCTION

Renal stones are a common health problem worldwide, with rising prevalence and high recurrence rates. Extracorporeal shock wave lithotripsy (ESWL) and percutaneous nephrolithotomy (PCNL) are established treatments. While ESWL is well studied for primary renal stones, its effectiveness for post-PCNL residual stones is less well defined.

OBJECTIVE

This study aims to compare the stone-free rate of ESWL in patients with post-PCNL residual stones versus those with primary renal stones of the same size (5-15 mm).

METHODS

This prospective cohort study was conducted at the Sindh Institute of Urology and Transplantation, Karachi, from January to July 2022. A total of 108 patients with solitary renal stones (5-15 mm) were enrolled into two equal groups: post-PCNL residual stones and primary stones. ESWL was performed using a Dornier Compact Sigma lithotripter, delivering 2,500-3,500 shocks per session at 60-90 shocks/minute, with energy titrated up to a maximum of 6 J according to patient tolerance. Stone-free status was defined as the absence of residual fragments >4 mm on ultrasonography and kidney-ureter-bladder X-ray at eight weeks.

RESULTS

The mean age of the cohort was 35.09 ± 10.72 years, mean BMI 25.06 ± 3.33 kg/m², and mean stone size 1.16 ± 0.27 cm. Overall stone clearance was achieved in 78 patients (72.2%). Clearance was significantly higher in the post-PCNL group (48/54; 88.9%) compared with the primary stones group (30/54; 55.6%) (p < 0.01). Patients with post-PCNL stones were more likely to be stone-free (relative risk (RR) 1.60, 95% CI 1.24-2.07). No major complications were observed; minor flank pain and transient hematuria occurred in 12% of patients and resolved conservatively.

CONCLUSION

ESWL achieved significantly higher stone-free rates in post-PCNL residual stones compared with primary renal stones of the same size. Given its safety, accessibility, and non-invasive nature, ESWL should be considered a first-line treatment option for small residual fragments following PCNL.