In simple words: The doctor widens an existing pathway between the kidney and the skin. They might leave a tube in place to keep it open. They also create a new pathway to the kidney. This procedure includes imaging guidance and expert interpretation.

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; including new access into the renal collecting system. (Do not report 50436, 50437 in conjunction with 50382, 50384, 50430, 50431, 50432, 50433, 52334, 74485) (For nephrolithotomy, see 50080, 50081) (For dilation of an existing percutaneous access for an endourologic procedure with a new access into the collecting system, use 50437; for additional new access into the kidney, use 50437 for each new access that is dilated for an endourologic procedure) (For endoscopic surgery, see 50551-50561) (For retrograde percutaneous nephrostomy, use 52334)

Example 1: A patient with a previous nephrostomy tube requires dilation of the tract to accommodate larger instruments for a stone removal procedure. A new access is created in the same session as the dilation., A patient with a blocked ureter requires a nephrostomy tube placement, and the existing tract needs dilation to facilitate the insertion of the tube., A patient undergoing a percutaneous nephrolithotomy requires dilation of the existing nephrostomy tract to allow for the passage of instruments and subsequent stone removal, and a new access is created.

Documentation should include details of the existing nephrostomy tract, the reason for dilation, the method used for dilation, the placement of a new access, the size and type of the nephrostomy tube placed, imaging guidance used, and any complications encountered.