[Ultrasonic examination in the treatment of renal calculi]

Ultrasound is used currently to confirm the presence of stones pre-operatively as well as allowing localization of stones during operation. The great value of this technique lies in its capacity to distinguish between a non-opaque stone and a tumour of the collecting system. X-rays are said to be useful for demonstrating residual stones during nephrolithotomy, but this has the limitation of allowing only 2-D localization. On the other hand ultrasound using a sound, set at 7.5 MHz, and held in the hand allows precise localization of the depth of the stone relative to the kidney surface. This technique makes it possible to introduce a needle to probe the stone before effecting its removal by way of a small nephrotomic incision. The surgeon employing this method should have sound experience in order to recognize the brilliant resonance and the acoustic shadow of a stone. This method, tested on 44 patients was successful in 26, failed in 11 and was considered helpful in 7.