Hello,
If you are billing for the procedure in which you take a respiratory sample (e.g., throat or nasal swab, nasal aspirate or sputum) and do the rapid test, you should submit 87804, “Infectious agent antigen detection by immunoassay with direct optical observation; Influenza.”
However, if you are using some other source (e.g., culture material) or technique, which would not generally be considered a “rapid” flu test, you should submit a different code, such as 87400, “Infectious agent antigen detection by enzyme immunoassay technique, qualitative or semiquantitative, multiple step method; Influenza, A or B, each.”
Regards,
LMohan