Pathology/Lab Coding Alert

Should Labs Use Modifier -91,-59 or None at All?

What's a coder to do when the lab performs different tests that use the same CPT code? Reporting the same code twice may be accurate, but it may not get you paid.

Some CPT Codes describe not just one lab procedure but several tests for different analytes, genetic components or other features. For example, if you perform multiple assays for different infectious-agent-antibody immunoglobulin classes, you should report each assay separately using the same CPT code for instance, three units of 86677 (Antibody; Helicobacter pylori) for H. pylori IgG, IgA and IgM. Similarly, if you perform biotin and niacin blood tests, report each test as 84591 (Vitamin, not otherwise specified).

But should you use modifier -91 (Repeat clinical diagnostic laboratory test) or -59 (Distinct procedural service) or none at all in these cases? The answer may depend on your payer. "From strictly a coding perspective, when you report multiple units of a single CPT code representing different tests, you should not have to use a modifier," says Anne Pontius, MBA, CMPE, MT (ASCP), president of Laboratory Compliance Consultants Inc., in Raleigh, N.C.

Some payers require a modifier in these cases to indicate that you are not duplicate-billing. "Unless your payer specifies otherwise, I would recommend using modifier -91 for scenarios such as multiple immunoglobulin classes reported with the same CPT code," says Kenneth Wolfgang, MT (ASCP), CPC, CPC-H, director of coding and analysis for National Health Systems Inc., a coding consultation company in Camp Hill, Pa.

This seems to be a topic of much debate, with some other experts recommending modifier -59 for this scenario because the test values represent different agents, not subsequent test values for the same agent. A presenter at the November 2002 American Medical Association CPT symposium stated, however, that -91 is the appropriate modifier in this case, Wolfgang says.

"Knowing whether or which modifier to use can be confusing," Pontius claims. "CMS wants it both ways. They want us to code appropriately, and they want us to use modifiers that don't really clarify what we've done but just allow us to get paid."

Perhaps CMS says it best in its CCI direction for coders (http://cms.hhs.gov/medlearn/ncci.asp): "In some instances, the use and interpretation of modifiers is different [for different carriers and fiscal intermediaries], even though the description of them is the same."