Question: Our pathologist performs a flow cytometry cancer study looking at CD45, CD34 and CD3. Our billing department says we should use a modifier to indicate that we have done a "repeat test" for the technical portion of this study. Should this be modifier 59 or 91? Although your billing department seems to consider 88185 a "repeat test" worthy of a modifier, that is not the case. Code 88185 is an add-on code that you must report in addition to 88184 whenever a flow-cytometry panel includes more than one marker. You should report 88185 for each marker beyond one because the code states "each additional marker."
Texas Subscriber
Answer: You should not use either modifier - 91 (Repeat clinical diagnostic laboratory test) or 59 (Distinct procedural service).
The proper way to code the study you describe is as follows: