Aim of the study: The choice of an extracorporeal lithotripter for extracorporeal shock wave lithotripsy (ESWL) of urinary stones must be done with efficacy criteria. It is easy to demonstrate the advantages of the third-generation lithotripters compared to previous generations of lithotripters. This study has the purpose of evaluate whether it is possible to establish differences in effectiveness between two third generation lithotripters.
Methods and results: We report about the last 100 ESWL treatments carried out with the Wolf Piezolith 3000 and the last 100 with the Storz Modulith SLK, performed by the same single operator. Stones were stratified by site and size. Comparison was made considering the number of shock waves per session and the number of sessions and the outcomes. The results showed no statistically significant differences. In fact, the cumulative stone-free rate was 93% for the Wolf Piezolith and 91% for the Storz Modulith.
Conclusions: The technical differences between lithotripters concern the energy delivered, the shape of the acoustic focus, the depth of focus, the coupling surface, the mobility of the head, the alignment mode and the simultaneous use of ultrasonography and radiological pointing. These differences are never obtained from published series. Furthermore data of patients and stones that have not been treated for the difficulty of stone targeting due to the depth of acoustic focus (high BMI), the limited inclination of the head or to the patient intolerance to shock waves are not usually reported. The results obtained by the same operator are comparable even when are obtained with different machines of the same generation. The real differences could arise if we would take into account also the patients which were excluded from evaluation because, for the same generation of lithotripters, the results depend on the operator, while the eligibility to treatment of the patient depends on the characteristics of the machine.