Extracorporeal shock wave lithotripsy for lower pole nephrolithiasis: Efficacy and variables that influence treatment outcome

ABSTRACT

We evaluated the efficacy of Extracorporeal Shock Wave Lithotripsy [ESWL] for treatment of lower pole caliceal stones. The study attempts to identify the relationship between the radiographic anatomy of the lower pole and the outcome of ESWL treatment for a solitary lower pole caliceal stones to help in selecting patients that are likely to benefit from that treatment. A total of 100 patients with solitary lower pole calculi [less than 2 cm.] underwent ESWL monotherapy using the Dornier Lithotriptor S machine. Pretreatment intravenous urography [IVU] was done to determine the stone size and lower pole measurements which include; the lower pole infundibular length. The lower pole infundibular width and the lower pole infundibulopelvic angle. Clinical and radiographic follow-up was done every month for 6 months after ESWL treatment. Sixty-four patients [64%] were stone-free 6 months after starting ESWL treatment, eighteen patients [18%] showed improvement as decreased stone size and another eighteen patients [18%] failed ESWL treatment. Significant variables that influenced treatment outcome include, stone size and type the number of ESWL sessions and the radiographic anatomy of the lower pole. A short and broad lower pole infundibulum were very important favorable factors that improved the stone clearance after ESWL. Also a wide infundibulopelvic angle significantly improves the stone free rate after ESWL.ESWL is the initial treatment of choice for lower pole calculi smaller than 2cm. The spatial anatomy of the lower pole as defined by the lower pole infundibulopelvic angle, infundibular length and infundibular width, has a significant role in stone free rates after ESWL