Impact of lower pole renal anatomy on stone clearance after shock wave lithotripsy: Fact or fiction?

Purpose: We determined whether there is a significant relationship between the spatial anatomy of the loser pole on preoperative excretory urography a nd stone fragment clearance after shock wave lithotripsy, Materials and Methods: The anatomical factors affecting lower pole stone cl earance after shock wave lithotripsy were evaluated retrospectively in 108 patients. Stone-free status was assessed by renal computerized tomography w ith or without renal ultrasound. The stone-free rate at 3 months was correl ated with lower pole infundibular length and width in mm. as well as with t he lower pole infundibulopelvic angle in degrees. The statistical significa nce of each lower pole anatomical factor as well as other stone, renal and treatment factors were correlated with the stone-free rate using the Mann-W hitney and chi-square tests. Results: Three months after shock wave lithotripsy 79 patients (73.1%) were free of stones. Mean lower infundibular length plus or minus standard devi ation was 20.9 +/- 6.56 mm., mean infundibular width was 5.65 +/- 2.34 mm, and the mean lower pole infundibulopelvic angle was 48.33 +/- 14.84 degrees . In 49 (45.4%) and 59 (54.6%) patients infundibular length was greater tha n 3 cm, and 3 cm. or less, respectively. Infundibular width was greater tha n 5 mm. and 5 mm. or less in 45 (41.7%) and 63 (58.3%) patients, respective ly. No obtuse infundibulopelvic angles were noted. None of the 3 lower pole anatomical factors had any significant impact on the stone-free rate at 3 months, Renal morphology was the only factor significantly affecting the st one-free rate since stone clearance was significantly less in pyelonephriti c kidneys (p = 0.0009). Conclusions: Differences in the intrarenal anatomy of the lower pole have n o significant impact on stone clearance after shock wave lithotripsy. Furth er examination of the lower pole renal anatomy with a search for other cont ributing factors is still warranted.