Anatomic Factors that Affect Lower Caliceal Stone Clearance after Shock Wave Lithotripsy

Sun, Young Bae; Kim, Young Hack; Kwon, Chil Hun

Abstract

PURPOSE: Shock wave lithotripsy(SWL) has become the preferred modality of treatment for the most kidney stones. But there is a consensus that success rate of SWL is relatively poor for the lower caliceal stones. We assessed the influence of spatial anatomy of the lower calyx on stone clearance after SWL.
MATERIALS AND METHODS
We retrospectively reviewed 92 patients with 5-20mm sized solitary lower caliceal stone who had undergone SWL between March 1992 and February 1998. The clearance rate at three months was compared according to lower pole anatomy, such as infundibulopelvic angle, infundibular length and infundibular width.
RESULTS
Overall stone free rate was 59.8 percent. In 67 cases whose infundibulopelvic angle greater than 90 degree, stone free rate was 68.7 percent, whereas in 25 cases less than 90 degree, it was only 36.0 percent(p<0.05). In 36 cases whose infundibular length greater than 3cm stone free rate was 38.9 percent, whereas in 56 cases less than 3cm it was 73.2 percent(p<0.05). In 70 cases whose infundibular width greater than 5mm stone free rate was 57.1 percent, whereas in 22 cases less than 5mm it was 68.2 percent.
CONCLUSIONS
The lower pole infudibulopelvic angle and infundibular length has a significant role in the stone clearance after SWL of lower caliceal stones. The infundibulopelvic angle less than 90 degree and infundibular length greater than 3cm are individually unfavorable factors. We believe that these anatomic factors have to be considered when the physician decides SWL as a first line treatment of lower caliceal stones.