Pathology/Lab Coding Alert

Question: Our lab sometimes runs multiple molecular diagnostic tests for the same patient on the same day, and we are having trouble with reimbursement in certain cases. For example, Medicare will not pay for 83898 and 83902 when billed together. Would this be a case in which you could use either the -GB or -59 modifier? What is the difference between the two modifiers?

Becky Brady
Molecular Pathology Services, Louisville, Ky.

Answer: According to the Correct Coding Initiative (CCI) edits, code 83898 (molecular diagnostics; amplification of patient nucleic acid [e.g., PCR, LCR, RT-PCR], single primer, pair, each primer pair) is mutually exclusive with 83902 (molecular diagnostics; reverse transcription) and therefore would not be reimbursed by Medicare when billed together.

Mutually exclusive means that these codes represent services or procedures that, based on either the CPT definition or standard medical practice, would not or could not reasonably be performed for the same patient on the same day. Therefore, Medicare will not pay for this code pair when reported together.

In this case, however, the superscript (1) that appears next to the 83898 in the CCI edits means that a modifier can be used to indicate that both services were provided, and may be considered for reimbursement if supported by medical necessity.

Use modifier -59 (distinct procedural service) to identify procedures/services that are not normally reported together, but are appropriate under the circumstances. This modifier may represent a different session or patient encounter, different procedure or surgery, different site or organ system, separate injury (or area of injury in extensive injuries) not ordinarily encountered or performed on the same day by the same physician. You may identify the secondary, additional, or lesser procedure or service by adding the -59 modifier. Do not use modifier -GB because it has been deleted and replaced with modifier -59 as of January 1997.

Answered by Laurie Castillo, MA, CPC, CPC-H, CCS-P, a member of the National Advisory Board of the American Academy of Professional Coders and president of its Northern Virginia Chapter.