In simple words: Widening of an existing pathway between the kidney and the skin for a urological procedure, using imaging guidance. A tube may be left in place afterwards.

Dilation of existing tract, percutaneous, for an endourologic procedure including imaging guidance (eg, ultrasound and/or fluoroscopy) and all associated radiological supervision and interpretation, with postprocedure tube placement, when performed.

Example 1: A patient with a pre-existing nephrostomy tract requires dilation of the tract to accommodate a larger nephroscope for stone removal. The urologist dilates the existing tract using imaging guidance and places a nephrostomy tube after the procedure. 50436 is reported., A patient has a nephrostomy tract created by an interventional radiologist. Later, a urologist dilates this existing tract for an endourological procedure, using imaging guidance, and places a new nephrostomy tube. 50436 is reported., A patient undergoes a PCNL (50080 or 50081) on the right kidney. During the same session, the urologist dilates a pre-existing nephrostomy tract on the left kidney for a separate procedure, using imaging guidance and placing a nephrostomy tube. 50436 is reported with modifier 59 or XU.

Documentation should clearly indicate the dilation of a pre-existing nephrostomy tract, the use of imaging guidance, the type of endourologic procedure planned, and post-procedure tube placement, if performed. The size of the instruments used and the final diameter of the dilated tract should be documented.