Interventional Radiology

Biliary Drainage – Exchanges, Conversions, Stents

As with most IR procedures, one of the primary issues faced when it comes to coding remains the inconsistent language in reports. Procedures can be described in a multitude of ways adding complexity and confusion to the process. Even though they may be performing the same procedure, physicians don’t (typically) have a uniform way of documenting what was done.

The issue of inconsistent language is even more apparent when it comes to biliary drainage procedures. Although it’s been a few years since the codes for these procedures were introduced, questions around drainage catheter exchanges, conversions and stent placements are among the most common we receive from coding professionals across the country.

When coding for these services, the primary question to ask about the documentation is: what did we start with, and what did we end with? By knowing those key points, we can work out the rest.

In order to understand the answers to the above question, we first need to master the different devices we can start and end with:

External biliary drainage catheter: A catheter placed in a bile duct that extends outside the body (external) to drain bile. This type of drainage catheter does not extend into the small intestine, it drains externally only.

Internal-external biliary drainage catheter: A catheter placed in a bile duct that extends outside the body (external) as well as extends into the small intestine (internal) to drain bile into the small intestine and/or externally.

Stent: For the purposes of this code set, a stent is a device that is percutaneously placed in the biliary system and is contained completely inside the body, no part extends outside the body or is externally accessible.

Once we know the type of device we are starting with and ending with we can determine the correct procedure for coding purposes.

An exchange refers to changing out the existing catheter for the same type of device or switching an existing internal-external catheter to an external catheter. A conversion refers to switching an existing external catheter to an internal-external catheter. If either of these types of existing catheters are switched for a completely internal drainage device, this is neither an exchange or a conversion; this is a stent placement through an existing access.

Start End Procedure CPT Code
External External Exchange47536
External Internal-External Conversion47535
External StentStent Placement47538
Internal-External Internal-External Exchange 47536
Internal-External External Exchange 47536
Internal-External Stent Stent Placement47538

Of course, reports aren’t always this clear cut, but being able to answer “what did we start with and what did we end with” goes a long way toward identifying the procedure performed and, from there, the appropriate CPT code.