Predictive factors of extracorporeal shock wave lithotripsy success for urinary stones

Objective To review with our experience the predictors of stone-free status after extracorporeal shock wave lithotripsy (ESWL) on urinary stones. Methods The records of 68 consecutive patients with urinary stones treated with ESWL were reviewed. Patient age, sex, body mass index (BMI), stone dimension, stone Hounsfield density (HD) and stone composition determined by infrared spectroscopic analysis were studied as potential predictors. Results Stone Hounsfield density and stone composition were found to be the only predictors of treatment outcome. Stones with lower mean HU levels were more successfully fragmented. The stone density threshold that best distinguished between the outcome groups was 1000 HU. Higher ESWL success rates were found with uric acid and calcium oxalate dihydrate stones. Conclusions The results of our study have shown that stone Hounsfield density and stone composition predict for ESWL success.