EXTRACORPOREAL SHOCK-WAVE LITHOTRIPSY TREATMENT OF LOWER CALICEAL STONES - AN UPDATE ON THE USE OF A COBRA CATHETER FOR DIRECT IRRIGATION

As the general experience with extracorporeal shock wave lithotripsy ( ESWL) for renal calculi broadens, it is increasingly evident that the clearance of stone fragments in lower pole calices needs to be improve d. The stone-free rate posttreatment for lower caliceal stones is cons istently less than that for other upper tract locations. Utilization o f a cystoscopically placed cobra catheter for directed irrigation duri ng ESWL with a Dornier HM4 lithotripter resulted in an increase of our lower caliceal stone-free rate to 64% (29/45) at 1 month follow-up an d 73% (33/45) at 3 months follow-up compared to 36% (15/42) of randoml y selected controls at 1 month (p < 0.007) and 54% (23/42) at 3 months (p < 0.070). Patients were included in the study if they had a solita ry calculus, < 2 cm in size, located in a normal lower pole calix and had no indwelling stent placed by the referring physician. The cobra c atheter was positioned in the appropriate calix with fluoroscopic guid ance under intravenous sedation. Statistical analysis was performed us ing Pearson's Chi-square test. We conclude that the pre-ESWL treatment placement of a cobra catheter into the lower pole calix and intermitt ent irrigation during the procedure is a useful adjunct in the success ful treatment of lower caliceal calculi.