Does lower-pole caliceal anatomy predict stone clearance after shock wave lithotripsy for primary lower-pole nephrolithiasis?

AIM: In order to have an idea about the success rates after extracorporeal shock wave lithotripsy (SWL) in patients with lower-pole stones, we reviewed the caliceal anatomy of the patients treated in our clinic.

PATIENTS AND METHODS: One hundred and ninety-eight patients having at least a 3-month follow-up period, with a single stone located in the lower pole, were included. Lower infundibulopelvic angle (LIP-A), infundibular width, and infundibular length were measured from standard intravenous urograms taken before initial ESWL.

RESULTS: One hundred and thirty patients (65%) were male, and 68 patients (35%) were female. We found no impact of age, sex, and affected side on the results of ESWL. The overall stone-free rate was 61.1% after 3 months of follow-up. The stone-free rates were 47.8 and 81.4% in patients with an acute (< 70 degrees) and an obtuse (> or = 70 degrees) LIP-A, respectively (p = 0.007). Taking the infundibular width into consideration, the stone-free rates were 85.4 and 43.2% for favorable and unfavorable angles and widths (p = 0.003). However, infundibular length and stone sizes were not found to have important effects on a stone-free status (p = 0.546 and p = 0.283).

CONCLUSION: We conclude that LIP-A (> or = 70 degrees) has the greatest impact on the clearance of residual fragments produced by SWL.