The aim of the procedure is to widen the abnormally narrowed part of the PUJ. With the patient under general anaesthesia and using fluoroscopic guidance, a device containing a monopolar diathermy wire on the surface of a low-pressure tamponade balloon is inserted through the ureter and into the PUJ. The balloon is partially inflated to determine the area of stenosis (seen as a waist in the balloon) and to fix it in position for incision. The diathermy wire incises the target area of the PUJ, through the wall of the ureter, into the periureteric fat. The balloon is fully inflated to apply pressure (tamponade) following incision to promote haemostasis. A stent is inserted across the PUJ, with the aim of maintaining patency, and is removed after several weeks.