Management of lower pole renal calculi: shock wave lithotripsy versus percutaneous nephrolithotomy versus flexible ureteroscopy

Current ureteroscopic intracorporeal lithotripsy devices and stone retrieval technology allow for the treatment of calculi located throughout the intra-renal collecting system. Difficulty accessing lower pole calculi, especially when the holmium laser fiber is utilized, is often encountered. Herein we review our experience where lower pole renal calculi were ureteroscopically managed by holmium laser fragmentation, either in situ, or by first displacing the stone into a less dependent position with the aid of a nitinol stone retrieval device. Lower pole stones less than 20 mm can be primarily treated by ureteroscopic means in patients: that are obese; have a bleeding diathesis; with stones resistant to shockwave lithotripsy (SWL); with complicated intra-renal anatomy; or as a salvage procedure after failed SWL. Lower pole calculi are fragmented with a 200 μm holmium laser fiber via a 7.5 F flexible ureteroscope. For those patients where the laser fiber reduced ureteroscopic deflection, precluding re-entry into the lower pole calyx, a 1.9 F nitinol basket is used to displace the lower pole calculus into a more favorable position, thus allowing for easier fragmentation. A nitinol device passed into the lower pole, through the ureteroscope, for stone displacement cause only a minimal loss of deflection and no significant impact on irrigation. Eighty-five percent of patients were stone free by IVP or CT scan performed at 3 months. Ureteroscopic management of lower pole calculi is a reasonable alternative to SWL or percutaneous nephrolithotomy (PNL) in patients with low volume stone disease. If the stone cannot be fragmented in situ, nitinol basket or grasper retrieval, through a fully deflected ureteroscope, allows for repositioning of the stone into a less dependant position, thus facilitating stone fragmentation.