CLINICAL IMPLICATIONS OF CLINICALLY INSIGNIFICANT STONE FRAGMENTS AFTER EXTRACORPOREAL SHOCK-WAVE LITHOTRIPSY

Purpose: We determined the natural history and clinical significance o f small, asymptomatic, noninfection related stone fragments after extr acorporeal shock wave lithotripsy (ESWL). Materials and Methods: We p rospectively followed 160 patients with 4 mm. or less asymptomatic cal cium oxalate/phosphate stone fragments after ESWL for 1.6 to 88.8 mont hs (mean 23) to stone-free status, censorship or intervention. Kaplan- Meier estimates of probability to anatomical stone-free, decreased or stable status were determined as well as the probability of symptomati c episodes or required urological intervention. Results: Stone-free st atus or a decreased, stable or increased amount of residual stone occu rred in 38 (23.8%), 26 (16.3%), 67 (41.9%) and 29 (18.1%) of the 160 p atients, respectively. At 5 years after ESWL the probability of a ston e-free, stone-free or decreased status, or stone-free, decreased or st able status was 0.36, 0.53, and 0.80, respectively. A total of 91 pati ents (56.9%) remained asymptomatic while 69 (43.1%) had a symptomatic episode or required intervention 1.6 to 85.4 months (mean 26) after ES WL (probability estimated at 0.71 at 5 years). Conclusions: While pati ents with small noninfection related stone fragments after ESWL may be followed expectantly, a significant number will require intervention or have symptomatic episodes within 2 years. The term clinically insig nificant applied to any residual stone after ESWL is likely a misnomer .