Intraoperative localization of renal calculi during nephrolithotomy by ultrasound scanning.

An ultrasound B-scan probe has proved to be useful in the intraoperative localization of renal calculi. The probe is small, readily available and produces an anatomical cross-sectional image of the kidney. The use of a 10 MHz. frequency probe enables 2 to 3 mm. stones to be detected readily. Calibration of the screen and the use of a fine needle inserted into the kidney under ultrasound control provide for precise 3-dimensional localization of the stone to facilitate its removal. The method has been successful in accomplishing the complete removal of small stones or residual fragments in 7 of 11 patients in whom it has been used. The method requires some experience in the use of the probe and in the interpretation of the ultrasound image.