COMPARATIVE ANALYSIS OF STONE-FREE RATES IN LOWER POLE RENAL STONES (<1.5 CM): ESWL VS. RIRS

Abstract

Background: Treating stones in the lower pole of the kidney is often difficult because certain anatomical features—such as an acute infundibulopelvic angle, elongated calyx, and narrow infundibular width—reduce the likelihood of effective drainage of fragments. Extracorporeal shock wave lithotripsy (ESWL) is widely used for small renal stones due to its non-invasive nature; however, its success rate for lower-pole calculi is often suboptimal. In contrast, retrograde intrarenal surgery (RIRS), facilitated by advances in flexible ureteroscopy and laser technology, has demonstrated improved stone clearance outcomes.

Objectives: This study is designed to evaluate and compare stone-free rates after ESWL and RIRS in patients with lower-pole renal stones measuring less than 1.5 cm.

Methods: A randomized controlled trial was conducted at PGMI/Lahore General Hospital involving 150 patients with confirmed lower-pole stones (<1.5 cm). Participants were randomly assigned to either the ESWL group or the RIRS group. Post-treatment outcomes were evaluated using a non-contrast CT KUB performed one week after the procedure. The primary outcome measure was the stone-free rate.

Results: Among the 150 patients, the RIRS group demonstrated a higher stone-free rate of 53.9% compared to 46.1% in the ESWL group. The difference was statistically significant (p = 0.036), indicating a favorable outcome with RIRS in this patient population.

Conclusion: RIRS showed superior efficacy compared with ESWL for treating lower-pole kidney stones measuring 1.5 cm or less. These findings support considering RIRS as a preferred option in selected cases, particularly when anatomical factors may limit ESWL success.