Nitinol stone retrieval-assisted ureteroscopic management of lower pole renal calculi

Objectives, Current ureteroscopic intracorporeal lithotripsy devices and st one retrieval technology allow for the treatment of calculi located through out the intrarenal collecting system. Difficulty accessing lower pole calcu li, especially when the holmium laser fiber is used, is often encountered. We retrospectively reviewed our experience with cases in which lower pole r enal calculi were ureteroscopically managed by holmium laser fragmentation, either in situ or by first displacing the stone into a less dependent posi tion with the aid of a nitinol stone retrieval device. Methods. Thirty-four patients (36 renal units) underwent ureteroscopic trea tment of lower pole renal calculi between April 1998 and November 1999. Low er pole stones less than 20 mm were primarily treated by ureteroscopic mean s in patients who were obese, in patients who had a bleeding diathesis, in patients with stones resistant to shock wave lithotripsy, and in patients w ith complicated intrarenal anatomy, or as a salvage procedure after failed shock wave lithotripsy. Lower pole calculi were fragmented with a 200-mum h olmium laser fiber by way of a 7.5F flexible ureteroscope. For those patien ts in whom the laser fiber reduced the ureteroscopic deflection, precluding re-entry into the lower pole calix, a 3.2F nitinol basket or a 2.6F nitino l grasper was used to displace the lower pole calculus into a more favorabl e position, allowing easier fragmentation. Results. In 26 renal units, routine in situ holmium laser fragmentation was successfully performed. In the remaining 10 renal units, a nitinol device was passed into the lower pole, through the ureteroscope, for stone displac ement. Only a minimal loss of deflection was seen. Irrigation was significa ntly reduced by the 3.2F nitinol basket, but improved with the use of the 2 .6F nitinol grasper. This factor did not impede stone retrieval in any of t he patients. At 3 months, 85% of patients were stone free by intravenous ur ography or computed tomography. Conclusions. Ureteroscopic management of lower pole calculi is a reasonable alternative to shock wave lithotripsy or percutaneous nephrolithotomy in p atients with low-volume stone disease. If the stone cannot be fragmented in situ, nitinol basket or grasper retrieval, through a fully deflected urete roscope, allows one to reposition the stone into a less dependent position, thus facilitating stone fragmentation. UROLOGY 56: 000-000, 2000. (C) 2000 , Elsevier Science Inc.