Morphology of renal pelvis and clearance of lower pole stones following ESWL

Abstract

A prerequisite for successful outcome of exatracorporeal shock wave lithotripsy (ESWL) is effective stone fragmentation. Despite successful stone fragmentation, complete clearance of stone fragments cannot be achieved in every patient, due to various factors. The aim of this prospective study was to determine morphological factors that affect clearance following successful stone fragmentation by ESWL. In the period October 1999 and January 2001, 60 patients (45 male and 15 female) with single lower pole kidney stones have been treated using lithotripter Lithostar 2000TM. Parameters of radiographic anatomy, measured on intravenous pyelography, included infundibular width and length, infundibuloureteral infundibulopelvic angles. After the follow-up period of 3 months, patients were divided into two groups regarding clearance status: Group I consisted of stone free patients, and group II of those with residual fragments. Average values of measured parameters in group I vs group II were as follows: infundibular length 27.70 +/- 5.48 mm vs 30.25 +/- 3.95 mm (p = 0.045, Mann-Whitney test); infundibular width 5.98 +/- 3.28 mm vs 4.70 +/- 1.30 mm (p = 0.018, Mann-Whitney test); infundibulopelvic angle 52.92 +/- 20.76 degrees vs 34.10 +/- 8.19 degrees (p = 0.00001, Mann-Whitney test); infundibuloureteral angle 48.00 +/- 21.13 degrees vs 30.70 +/- 7.49 degrees (p = 0.00001, Mann-Whitney test). This study revealed that parameters of infundibulopelvic anatomy were significantly different in the examined groups. The success of clearance of fragments following ESWL procedure can be predicted using these morphologic parameters.