[Real-time ultrasonography. Application to the intra-operative location of renal calculi].

Real-time ultrasonography was used intra-operatively in 12 cases of renal lithiasis, in association with radiography. The 10 MHz instrument with sectorial probe is small and easy to sterilise. Calculi larger than 2 mm (including radiotransparent ones) were detected by this method in 10 patients. One of the two failures was due to the surgical incision hindering the positioning of the probe, and the other to the presence of air after pyelotomy of a dilated renal pelvis in front of a horseshoe kidney. Ultrasonography appears to be a sensitive method allowing tridimensional location of small calculi, even when they are transparent to X-rays. The site and size of nephrolithotomy can be selected according to the thickness of renal tissue and to the presence of arteries, also visible on ultrasounds. The operating time is shortened and the risk of residual lithiasis is reduced. Owing to the possibility of artefacts, such as air bubbles, suture material and clots, contact radiography should be combined with ultrasonography, at least for roughly locating the stones.