Answer: If your lab only performs a total count for B cells, you should not bill a flow cytometry interpretation. Instead, you should report 86355 (B cells, total count) for the service. Even if the lab uses flow cytometry methods, quantitative cell counts don't require a physician interpretation.
Use 86355-86367 when the lab runs a quantitative flow cytometry test or panel for immunodeficiency, immune dysfunction and related analyses.
Watch out: What if the lab performs a total count for an unlisted cell type as part of an immunodeficiency panel? You should not use a code from the flow cytometry section, but instead use 86586 (Unlisted antigen, each) for unlisted cell types for quantitative analysis used to evaluate patients for immune dysfunction.
Do this: Reserve the flow cytometry codes (88184-88189) for when your pathologist performs and/or interprets flow-cytometry studies for immunophenotyping of hematolymphoid cancers. Use 88184 (Flow cytometry, cell surface, cytoplasmic, or nuclear marker, technical component only; first marker) and +88185 (- each additional marker [list separately in addition to code for first marker]) for the study's technical component.
The final step: For the pathologist's professional interpretation of the panel, select the appropriate interpretation code based on the number of markers in the panel: 88187 for two to eight markers, 88188 for nine to 15 markers, and 88189 for 16 or more markers. Select one code to describe the interpretation of all flow cytometry markers for a single specimen.
Don't mix and match: Your question asked about using 88187 for the total B cell count interpretation. You should not mix and match the immunology section codes and the flow cytometry codes. The total B cell count would normally require no interpretation, but if the ordering physician requests a consultation on the results, report that service with 80500 (Clinical pathology consultation; limited, without review of patient's history and medical records). The National Correct Coding Initiative bundles 86355 and 80500, however, so if you have documentation to support reporting both codes, you should use modifier 59 (Distinct procedural service) with 80500.