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 is the infundibulopelvic angle, but its measurement is complex.

METHODS

We proposed a more simple measure of caliceal dependence, the caliceal pelvic height (CPH), which we defined as the distance between a horizontal 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 > or = 15 mm, the clearance rate was only 52% (p < 0.05). A majority (74%) of the patients with an infundibular width of > or = 5 mm were rendered stone free compared with 40% of those with a width of < 5 mm (p < 0.05).

CONCLUSION

Measurement of the CPH, in conjunction with other anatomic factors, may more accurately predict the outcome of SWL in patients with lower pole stones.