Lower-pole caliceal stone clearance after shockwave lithotripsy, percutaneous nephrolithotomy, and flexible ureteroscopy: impact of radiographic spatial anatomy.

Spatial anatomy of the lower renal pole, as defined by the infundibulopelvic angle (LIP angle), infundibular length (IL), and infundibular width (IW), plays a significant role in the stone-free rate after shockwave lithotripsy. A wide LIP angle, a short IL, and a broad IW, individually or in combination, favor stone clearance, whereas a LIP <70 degrees, an IL >3 cm, or an IW < or =5 mm are individually unfavorable. When all three unfavorable factors or an unfavorable LIP and IL coexist, the post-SWL stone-free rate falls to 50% or less. Using these criteria, more than one fourth of our patients with a lower-pole calculus might have been better served by an initial percutaneous or perhaps ureteroscopic procedure, neither of which is significantly affected by the lower-pole spatial anatomy.