Good point...below is the difference between the two~
CPT code for the rapid flu test
QWhat CPT code should I submit for the rapid flu test?
AIf 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." This is a new code that went into effect Jan. 1, 2002. 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."