Pathology/Lab Coding Alert

2. Count Markers Before You Assign Codes

Counting markers sounds easy enough, but there are some pitfalls, says LuAnn Lubell, MT (ASCP), systems analyst with Ohio Health in Columbus. When you see a flow cytometry panel that lists different antibodies, such as CD5, CD10 and CD19, the count is straightforward - three markers.

But sometimes the lab uses the same antibody in various multi-color tubes that comprise a panel, and may also use the antibody for "gating," which involves finding a specific population of cells by looking at the repeat antibody in combination with other antibodies. "Gating and multi-color tubes have led to some questions about how to count the markers," Lubell says.

Labs commonly evaluate the same antibody in multiple combinations. "We often run a tube with CD5/CD19, as well as evaluating CD5 alone and CD19 alone," says Walt Williams, billing and reimbursement specialist with Genoptix in San Diego. Although that's two antibodies in the first tube and one antibody in each subsequent test, for a total of four antibodies, "we bill the test as two markers," Williams says.

How to do it: For flow cytometry coding, don't count repeat antibodies. "Until we introduce a unique antibody into the assay, we don't code it separately," Williams says. When you code a flow cytometry report, you should count each unique CD# (or other marker name) that you see, and never count the same marker name more than once.

Although a lot of technical work goes into gating multiple antibodies, the thinking behind the CPT technical codes for flow cytometry is "per antibody," Williams says. "That means we bill for individual antibodies, not for analyzing repeat antibodies in different combinations," he says.

3. Assign Technical Code(s)

CPT 2005 provides two codes for the technical component of flow cytometry - that is, the work done to prepare the specimen and run the test.

"Codes 88184 and 88185 are in the cytopathology section, and you should use them to report the technical component of flow cytometry studies performed for immunophenotyping of hematolymphoid cancers," says Peggy Slagle, CPC, billing compliance coordinator at the University of Nebraska Medical Center in Omaha. The technical codes do not stand alone - you'll always report an interpretation code as well.

The new codes allow you to bill "per marker" for flow cytometry technical work. "Regardless of the number of markers in a flow cytometry study, you should always report one unit of 88184 for the first marker," Slagle says. "Additionally, you should report one unit of 88185 for each subsequent marker." A text note in CPT 2005 explains that 88185 is an add-on code and that you must use it in conjunction with 88184.

Tip: Medicare pays 88184 and 88185 under the Physician Fee Schedule - but lists no value for the physician work. "These are technical-only codes," Slagle says. Unlike old code 88180, you should not list 88184 and 88185 with modifier -TC (Technical component).

4. Choose 1 Interpretation Code

When you report 88184 and 88185 for flow cytometry technical work, you also have to select the appropriate interpretation code to bill for the pathologist's professional service.

CPT 2005 provides three interpretation codes based on the number of markers in the panel: 88187 for 2-8 markers, 88188 for 9-15 markers, and 88189 for 16 or more markers. "You should select one code to describe the interpretation of all flow cytometry markers for a single specimen," Slagle says.

As with the technical codes 88184 and 88185, the Physician Fee Schedule does not list interpretation codes 88187-88189 with any modifiers. That means you no longer use modifier -26 (Professional component) to indicate the professional service, as you used to when you reported flow cytometry with code 88180.

Red flag: CPT 2005 does not provide a code for interpretation of one marker, so don't bill for it. "Flow cytometry panels typically have multiple markers, so this limitation should not be a problem," Slagle says.

If the pathologist evaluates one flow cytometry marker, you would only report 88184 for the service.

5. Beware of Multiple Specimens for Flow Cytometry

Don't report flow cytometry on two (or more) specimens unless you can document medical necessity for both.

Medicare considers multiple flow cytometry specimens on the same date of service duplicate testing, "unless the morphology or other clinical factors suggest differing results on the different specimens."

You shouldn't even report flow cytometry on one specimen and an immunohistochemistry (IHC) stain (88342, Immunocytochemistry, each antibody) on a similar specimen on the same date, because the tests provide similar diagnostic information.

According to Medicare, similar specimens include:

1. blood and bone marrow;

2. bone marrow aspiration and bone marrow biopsy;

3. two separate lymph nodes; or

4. lymph node and other tissue with lymphoid infiltrate.

If the pathologist had to interpret multiple specimens for flow cytometry and/or IHC stain to reach a diagnosis, you can report both services. "The pathology report must document the need for both services, and you must use modifier -59 (Distinct procedural service) if you want to get paid for both," Slagle says. 

6. Use Immunology Codes for Total Counts

When labs perform flow-cytometry immunology tests that do not require professional interpretation, you should not use the new 88184-88189 series to report the service.

For example, the pathologist does not interpret  flow cytometry, total cell count panels that a physician orders to evaluate a patient's immunodeficiency or transplant status.

Extra: CPT 2005 lists three new immunology codes to report cell counts that your lab might perform using flow cytometry methodology. The pertinent immunology codes are the subject of a separate article at right, "Use 86586 for Unspecified Immunology Counts."