The radiolucent ureteric calculus at the end of a contrast-medium column: where to focus the shock waves.

OBJECTIVE: To compare the outcome of two different targeting strategies for treating radiolucent ureteric calculi by extracorporeal shock wave lithotripsy (ESWL), focusing the shock waves either at the end or 5 mm beyond the column of contrast medium visible in the ureter. PATIENTS AND METHODS: A total of 156 patients undergoing ESWL for a radiolucent ureteric stone were randomized into two groups. Group 1 comprised 74 patients in whom the shock waves were focused on the end of the contrast medium column, and group 2 comprised 82 patients in whom the shock waves were focused 5 mm beyond the end of the column.
RESULTS: Both groups had comparable distributions of age, gender, treatment methods and stone characteristics. There were no adverse reactions to the contrast medium. The stone-free rate after 2 months was 17% greater in group 2 (91%) than in group 1 (74%; P < 0.05).
CONCLUSIONS: The administration of intravenous contrast medium for ESWL of radiolucent ureteric calculi is effective and safe. We recommend that the shock waves are focused 5 mm beyond the end of the column of contrast medium, except where a stone becomes clearly visible within the column.

RCT Entities:   Population Interventions Outcomes