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

## TL;DR

This study found that shock wave therapy is more effective for kidney stones left after surgery than for original stones of the same size.

## Contribution

The study provides new evidence that ESWL is more effective for post-PCNL residual stones than primary stones of similar size.

## Key findings

- ESWL achieved a 88.9% stone-free rate for post-PCNL residual stones compared to 55.6% for primary stones.
- Patients with post-PCNL stones were 1.6 times more likely to be stone-free than those with primary stones.
- No major complications were observed, with only minor issues like flank pain and hematuria.

## Abstract

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.