MDS FISH

Medicare covers up to four initial MDS FISH probes (-7/del(7q), -5/del(5q), +8, del(20q)) for patients whose bone marrow is suggestive of MDS only when conventional karyotyping is inadequate (fewer than 20 metaphases or unresolved karyotype), with additional reflex probes allowed only if the initial four are negative or diagnostic uncertainty persists; FISH is not covered when an adequate karyotype exists, for other disorders, for repeat testing on the same specimen, or when NGS is used for diagnosis. Follow-up single-probe FISH without chromosome analysis is covered only with documentation of a prior MDS diagnosis with that specific genetic anomaly, and the report must state diagnostic/prognostic significance, percent abnormal/normal cells and cell type(s), probe names/manufacturer, and any assay limitations.

"More than 20 metaphases and a resolved karyotype preclude FISH testing."