The Factors Affecting Stone Clearance after Shock Wave Lithotripsy for Lower Calyceal Stones

Kim, Ki Ho; Kim, Dae Gon; Lee, Kyung Seop; Seo, Young Jin

Abstract

PURPOSE: The influence of the stone size and spatial anatomy of the lower pole was evaluated in relation to the stone clearance after shock wave lithotripsy (SWL) for lower calyceal stones.
MATERIALS AND METHODS
SWL monotherapy was performed in 44 patients, with lower calyceal stone, using a Dornier Compact-S lithotriptor. The study was comprised of a retrospective analysis of 44 patients. The patients were divided into 2 groups, 33 who were considered to be clear of fragments 3 months after SWL, and 11 who had residual stones. The infundibulopelvic angle, infundibular width and length of lower calyces were determined from intravenous urograms. The stone-free status was assessed 3 months after the last shock wave lithotripsy session.
RESULTS
The mean lower calyceal stone size, lower calyceal infundibulopelvic angle and lower calyceal infundibular length and width were 10.2mm, 32.2 degrees, 27.3mm and 5.7mm, respectively. The overall success rate was 75.0%. Success rates for the patients with an infundibulopelvic angle more than 30 degrees and less than 30 degrees were 85.2 and 52.9% respectively. For those with infundibular length more than 30mm and less than 30mm were 78.3 and 71.4%, respectively. For those with an infundibular width more than 5mm and less than 5mm were 76.5 and 74.1%, respectively.
CONCLUSIONS
A low calyceal infundibulopelvic angle and the stone size had significant impacts on the stone clearance following shock wave lithotripsy. However, the infundibular length and width were not statistically significant factors associated with the stone clearance. Further examination of the lower pole renal anatomy, with a search for other contributing factors, is still warranted.