EFFICACY OF THE DORNIER LITHOTRIPTER S MACHINE FOR 100MM2 - 400MM2 RENAL CALCULI.

Introduction : Little has been written with regard to the efficacy of third generation extracorporeal shock wave lithotripsy (SWL) machines in the treatment of renal calculi between 100 to 400mm2. We present retrospective data on the Domier Lithotripter S, specifically looking at safety, efficacy, and the influence of pre-treatment stenting on the incidente of complications. Method : Of 699 patients with renal calculi who had undergone SWL, 100 were identified with single stones between 100mm2 and 400mm2 and utilised for further analysis. 22 had ureteric stents inserted prior to SWL with a further 2 having a nephrostomy. Result : The median number of treatments per calculus was 2 with a mean number of shocks per treatment of 2844 at an average power of 67%. 72% of treatments were successful defined as stone free [ n= 42], or residual fragments less than 4mm in diameter [ n = 30]). Failure was observed in 28% of cases where ancillary therapies (flexible ureterorenoscopy or percutaneous nephrolithotomy) were required. 'Whilst no statistical difference could be demonstrated between the outcome and size or site of calculus, the mean area of stone undergoing successful treatment was 155mm compared to 171mm2 in those where treatment failed. Two patients required nephrostomies for an infected obstructed system and two for steinstrasse. There was no statistical difference in either success or complications between patients with ureteric stents and those without (P-value 0.11). The mean size of calculus in patients without complications was 157mm2 compared to 188mm2 in those with (P-value 0.16). Conclusion : The Domier S lithotripter provides safe and effective first line treatment of renal calculi between 100mm2 to 400mm2. Whilst the stone-free rate is relatively low, the low complication rate supports our use of SWL compared with more invasive treatments. Pre-treatment placement of a ureteric stent does not appear to confer a benefit.