A nephrostomy is an opening between the kidney and the skin. A nephrostomy tube is a thin plastic tube that is passed from the back, through the skin and then through the kidney, to the point where the urine collects. Its job is to temporarily drain the urine that is blocked. This allows the kidney to function properly and protects it from further damage. It also helps clear any infection.

Ultrasound and/or X-ray images (or pictures) are used to guide the procedure. Contrast is injected into the part of the kidney that collects the urine. This enables the tube that will drain the kidney to be inserted into the collecting system in the best position.