Skin-to-stone distance (SSD) could provide a useful way to predict the success of extracorporeal shock wave lithotripsy (ESWL), researchers reported at the World Congress of Endourology and SWL in Istanbul, Turkey.
Dong Hoon Ko, MD, of Konyang University College of Medicine in Dae-jeon, Korea, and colleagues studied 43 patients who underwent ESWL and divided them into a success group (33 patients) and a failure group (10 patients) based on whether or not they had residual stones visible on computer tomography or simple X-ray within six weeks of treatment. The success group had a shorter mean skin-to-stone distance than the failure group (78.25 vs. 92.03 mm). Multivariate analysis showed skin-to-stone distance to be the only significant independent predictor of ESWL stone-free rate.
All patients had a single stone. The average stone size in the success and failure groups was 10.55 and 12.9 mm, respectively. In 28 patients, the stone was more than 10 mm wide.