Minimally Invasive Ureteroscopy Using Adjustable Electrohydraulic Lithotripsy

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Abstract
Eighty-five ureteroscopies and electrohydraulic lithotripsies were performed using semirigid ureteroscopes of 6.5F outer diameter and probes of 2.4F and 3.3F. Prototypes of new lithotripters were employed with the option to set the energy infinitely within a range of approximately 250 mJ to 1400 mJ per pulse. Increased energy was provided by a rise in the voltage, thus modifying the peak pressure and the initial slope of the shock wave according to our previous tests. One-third of the stones were located in the upper ureter, 15% in the middle, and 46% in the lower ureter. Half of the patients had been previously treated with the Dornier MFL 5000 without success. More than 85% of the manipulations were performed under local anesthesia. Stone contact was achieved in 99%, and lithotripsy was fully successful in more than 90% with an average energy per pulse of 450 mJ. In 7%, partial disintegration was achieved, and the residual stone was flushed back into the renal pelvis and effectively treated by extracorporeal lithotripsy. One stone had to be removed by open surgery. There were no major complications from the use of electrohydraulic lithotripsy. One perforation resulted while trying to pass the endoscope, but no strictures were seen in the follow-up of 6 months. An indwelling stent was placed only in 48% of the cases, when the stone burden or an inflamed stone bed seemed to make it necessary.