The blockage is treated surgically by a procedure known as pyeloplasty.
This consists of removing the obstructed or blocked part of the ureter and sewing the ureter back onto the pelvis (called an anastomosis). This is done to provide a wide passage for the urine to pass through.
With this procedure the UPJ is positioned anterior to the crossing artery to avoid further kinking of the ureter.
A piece of hollow plastic tubing called a ureteric stent is left between the pelvis and the bladder to allow the urine to pass through while the tub heals. This is normally removed after 6 weeks