Billing Flow Cytometry/Immunohistochemistry Codes

There are times a flow cytometry study is performed and is inconclusive, so immunohistochemical (IHC) stains are done.  Can they be billed together?  Yes, you can bill them in some circumstances with proper documentation but there are specific guidelines on the billing of these services.
 
The NCCI Manual says the billing of IHC stains with flow cytometry aren’t justified on the same day unless they’re for different medical conditions, or (1) one test is nondiagnostic, or (2) the first method doesn’t explain the H&E findings. NCCI also says the same immunologic technique isn’t billable on two or more related specimens with a case under normal circumstances.

NCCI goes on to say “Medicare does not pay for duplicate testing. Immunocytochemistry and flow cytometry should not in general be reported for the same or similar specimens. The diagnosis should be established using one of these methods.”

Unlike most edit pairs that you can override if you perform the procedures on different specimens, that’s not necessarily the case with these codes because the Policy Manual gives you examples of similar specimens which are:
• blood and bone marrow
• bone marrow aspiration and bone marrow biopsy
• two separate lymph nodes
• lymph node and other tissue with lymphoid infiltrate

If both are done, the pathologist must document in their medical report why both an IHC and flow cytometry study are medically appropriate on the same day for a particular case, or why IHC on related specimens is justified by NCCI standards. If documentation supports IHC and Flow then both can be reported by appending -59 modifier (or modifier XU) to code 88342, 88360 or 88361.

Documentation should be very specific. Some comments from The Pathology Service Coding Handbook which may be acceptable could be:
· “Flow cytometry was inconclusive results; therefore, suitable IHC stains were evaluated to finalize the diagnosis.”
· “Suitable IHC stains were evaluated to subtype the B-cell lymphoma that was identified by flow cytometry analysis.”
· “The phenotype for this patient is not clear by flow cytometry; therefore, a small panel of IHC stains for CD3, CD5, CD79A and CD138 is performed to characterize the process observed by light microscopy.”
· “A monoclonal B-cell population was detected by flow cytometry. Suitable IHC stains were evaluated to determine if monoclonal plasma cells were also present.”

This is only a CMS guideline.  The AMA doesn’t restrict Flows to a single specimen nor does it challenge the reporting of IHC and Flows on the same or similar specimens.  Be aware other payers may have a policy similar to Medicare.  But with further education on proper documentation it may be appropriate to report the services.