Objective: The aim of this randomized study was to assess the relation between shockwave frequency, sedation, and efficiency in piezoelectric extracorporeal shockwave lithotripsy (SWL) for ureteral calculi.
Methods: A random sample of 114 patients aged between 15 and 74 (mean 45) years were treated at the shockwave frequencies of 1 (N = 57) or 4 (N = 57) per second using the EDAP LT 02 lithotripter at maximum energy. The stones' largest diameter ranged from 5 to 18 mm (mean 7.6 mm). Lower ureteral stones were treated with the patient in the prone position and upper ureteral stones in supine position. The duration of SWL sessions and stone measurements were statistically similar for patients treated at low and high frequencies. The levels of required sedation (none, intramuscular analgesia, intravenous sedation-analgesia) and stone-free rates after one session were analyzed by Student's t-test or Fisher's exact test.
Results: Sedation did not differ statistically with SWL frequency for mid and lower ureteral calculi. However, the use of intravenous sedation-analgesia was less common for patients with upper ureteral stones treated at low rather than high frequency (19% and 100%, respectively; P < 0.0001). The success rate was significantly lower (P = 0.04) for lower ureteral calculi treated at low v high frequency (65 % and 89%, respectively) but was not statistically affected by frequency for upper ureteral stones.
Conclusion: We recommend high frequency for piezoelectric SWL of lower ureteral calculi, especially for stones with a maximum diameter > or =8 mm. On the other hand, low-frequency SWL appears to be suitable for the treatment of upper ureteral stones.