Electromagnetic extracorporeal shock wave lithotripsy for calculi in horseshoe kidneys.

Between June 1987 and January 1991, 11 renal units in 10 patients with horseshoe kidneys were managed by electromagnetic extracorporeal shock wave lithotripsy (ESWL) monotherapy with a Siemens Lithostar. A total of 33 calculi was treated in 42 sessions. All treatments were performed without anesthesia and on an outpatient basis. All calculi could be targeted by standard installation techniques. The maximum number of shock waves per session was 4,000, which implies per stone an average of 1.3 sessions and an average of 4,903 shock waves (range 1,800 to 9,000) at a mean energy setting of 17.8 kv. Complete disintegration or fragmentation into spontaneously passable particles was achieved in 27 calculi, for a success rate of 83% when considering the results in regard to the individual stone locations. Per renal unit, an average of 3 calculi were targeted and after an average of 3.8 sessions 6 units became stone-free. Horseshoe kidneys, when calculous, contain dispersed and multiple calculi and from these data approximately 1 session per stone must be planned. The number of treatments per renal unit increased in proportion to the number of calculi and to the presence of calculi with low fragility. Of 21 lower pole calculi 18 completely evacuated and this observation has been related to the more medial location of the inferior calices near the ureteropelvic junction. No impaired drainage of fragments was noted to be related to the horseshoe anatomy. Patency of the ureteropelvic anatomy appeared to be the main parameter for the evacuation of fragments. Neither preoperative nor postoperative adjuvant maneuvers have been necessary.