RADIOGRAPHIC PROGNOSTIC CRITERIA FOR EXTRACORPOREAL SHOCK-WAVE LITHOTRIPSY - A STUDY OF 485 PATIENTS

Objectives. We studied 485 patients treated by extracorporeal shock-wa ve lithotripsy (ESWL) using an ultrasound electrohydraulic apparatus i n an effort to define radiographic criteria for better patient selecti on for ESWL. Methods. Results were assessed according to plain x-ray n ephrotomography and ultrasound. The criteria for measuring success (st one free [SF]) excluded all residual fragments. After per-criteria ana lysis of the results, a multivariate analysis as well as an analysis o f stone composition by infrared spectroscopy were performed. Results. The SF rate was 57.5% (279 of 485). Calculi that were smooth, denser t han bone, located in the lower calyx, and larger than 15 mm had less s atisfactory results despite a greater number of impulses. A correlatio n was established between the radiographic appearance of the calculus, its composition, and ESWL results. Rough, less dense calcium oxalate dihydrate yielded satisfactory results (65%), whereas smooth, dense ca lcium oxalate monohydrate led to less conclusive results (41%). Multiv ariate analysis demonstrated the predominant influence of radiographic calculus profile on the results: rough, less dense calculi yielded a 79.4% SF rate, whereas smooth, dense calculi yielded a 33.6% SF rate. Conclusions. We propose that patients with dense, smooth calculi locat ed in the lower calyx and larger than 15 mm be treated by other techni ques, such as percutaneous nephrolithotomy. This would not only increa se the ESWL effectiveness rate, but would also reduce the cost of trea ting kidney stones.