Is there a simpler method for predicting lower pole stone clearance after shockwave lithotripsy than measuring infundibulopelvic angle?

Background and Purpose: Several anatomic factors influence the clearance of lower pole stones treated with shockwave lithotripsy (SWL), One of these i s the infundibulopelvic angle, but its measurement is complex. Methods: We proposed a more simple measure of caliceal dependence, the cali ceal pelvic height (CPH), which we defined as the distance between a horizo ntal line from the lowermost point of the calix containing the stone to the highest point of the lower lip of the renal pelvis. Results: In 62 patients who had SWL for solitary lower pole stones, a CPH < 15 mm was associated with a stone clearance rate of 92%, whereas with a CPH greater than or equal to 15 mm, the clearance rate was only 52% (p < 0.05) , A majority (74%) of the patients with an infundibular width of greater th an or equal to 5 mm were rendered stone free compared with 40% of those wit h a width of <5 mm (p < 0.05), Conclusion: Measurement of the CPH, in conjunction with other anatomic fact ors, may more accurately predict the outcome of SWL in patients with lower pole stones.