Select a Single Code when Tracing a Sentinel Node

By G. John Verhovshek, MA, CPC
Sentinel nodes are the first lymph nodes to receive drainage from nearby cancerous tissue. Biopsy of these nodes allows for early detection of a cancer’s spread.


To locate a sentinel node precisely for biopsy, the radiologist injects technetium-99m (Tc-99m) (a radioactive tracer) near the tumor. The tracer drains with the lymphatic fluid to the sentinel node, where it is absorbed.
If the operating surgeon uses a handheld counter (often called a gamma probe) to track the tracer and identify the sentinel node, the radiologist should claim CPT® code 38792 Injection procedure; for identification of sentinel node for the injection only.
“In some cases, the physician will only perform the injection of the radioactive tracer … When identification through injection of a radioactive tracer of a sentinel node(s) is performed without scintigraphy imaging, report code 38792,” confirms CPT® Assistant (Vol. 9, Issue 12).
If the radiologist supplies the Tc-99m filtered sulfur colloid tracer at his own cost, he may report also HCPCS Level II code A9541 Technetium Tc-99m sulfur colloid, diagnostic, per study dose, up to 25 millicuries.
The surgeon would not code separately for use of the gamma probe, as it is considered incidental to the sentinel biopsy.

Separate Services

If the surgeon injects blue dye (such as isosulfan blue) to identify the sentinel node, he or she would also report 38792. If a payer denies either the radiologist’s or surgeon’s injection as a duplicate service, the affected physician should appeal the rejection with an explanation that the radioactive tracer injection and the blue dye injection represent separate (and separately billable) services. To avoid confusion, some payers instruct the radiologist to submit a claim for 38792 first, and the surgeon to submit a subsequent claim for 38792 with modifier 77 Repeat procedure by another physician appended.

Professional Component

A gamma camera (unlike the gamma probe) provides multiple static images from different angles to pinpoint the sentinel node’s location. The radiologist marks the node’s location on the skin so the surgeon can identify it.
If the radiologist provides the radiotracer injection as described above, but also uses a gamma camera to capture dynamic, real-time images mapping the tracer’s path and sentinel node uptake, the radiologist would instead report 78195 Lymphatics and lymph nodes imaging with modifier 26 Professional component appended.
The radiologist may still report A9541 in addition to 78195 if he or she supplies the Tc-99m tracer for injection.
The radiologist should not, however, report 38792 in addition to 78195. The injection is included in the more extensive lymphoscintigraphy. “The injection of radioactive tracer is included in the lymphoscintigraphy procedure performed at the same session and is not reported separately. It is inappropriate to report 38792 when lymphoscintigraphy is performed,” instructs CPT® Assistant (Vol. 9, Issue 12).
When the radiologist claims 78195, the operating surgeon may separately report 38792 to describe a separate injection of isosulfan blue for direct visualization. The radiotracer injection, however, is always included in 78195.
G. John Verhovshek, MA, CPC, is AAPC’s director of clinical coding communications.

No Responses to “Select a Single Code when Tracing a Sentinel Node”

  1. Daryl Minggia says:

    What if the surgeon is injecting the isotope in the OR? Who would bill for the isotope charge/injection?