[Radiological aspects and results of percutaneous ultrasonic nephrolithotripsy].

Percutaneous removal of renal stones is becoming an established procedure, especially for stones lying free in the renal pelvis. These techniques, which include: retrograde pyelography to facilitate a thorough understanding of caliceal anatomy and stone position in 3 dimensions; approaches for accurate placement of a nephrostomy tract for straightline access to the stone and stone removal are discussed.