Cytogenetic Studies — NCD 198 | CMS Coverage Update

CMS Modified NCD 198 for Cytogenetic Studies, effective March 7, 2026. Here's what billing teams need to know before claims start moving through the system.

The Centers for Medicare & Medicaid Services (CMS) updated National Coverage Determination NCD 198, which governs Medicare coverage of cytogenetic studies — the microscopic examination of human chromosomes. This is a modification to an existing coverage policy, not a new determination, and the change took effect March 7, 2026. The policy does not list specific CPT or HCPCS codes in the current version, which creates a documentation burden your billing team needs to address now.

Quick-Reference Table

CMS Cytogenetic Studies Coverage Criteria and Medical Necessity Requirements 2026

Under NCD 198, Medicare covers cytogenetic studies when they are reasonable and necessary for the diagnosis or treatment of a defined set of conditions. The coverage policy is narrow and specific — this is not a broad authorization for chromosome studies generally.

The five covered indications are:

That's the list. If your patient's diagnosis doesn't map to one of those five buckets, Medicare reimbursement is off the table under this NCD. There's no prior authorization requirement mentioned in the policy, but the absence of prior auth doesn't mean documentation doesn't matter — it absolutely does.

The medical necessity standard here is "reasonable and necessary for the diagnosis or treatment" of those conditions. That phrase does a lot of work. Your documentation needs to tie the cytogenetic study directly to one of the listed conditions, not just reference the study in isolation. If you're billing for CML cytogenetics, the ordering physician's notes need to make that connection explicit.

Coverage Indications at a Glance

CMS Cytogenetic Studies Exclusions and Non-Covered Indications

NCD 198 doesn't provide an explicit exclusions list in the traditional sense, but the structure of the policy functions as one. Coverage is limited to the five enumerated conditions — anything outside that list is not covered under this NCD.

That matters more than it sounds. Clinical genetics has expanded significantly since the original NCD framework was written. Studies ordered for solid tumor genomics, pharmacogenomics, or inherited cancer risk assessment — none of those map to NCD 198's covered indications. If your oncology team is ordering cytogenetics in the context of breast cancer or lung cancer workups, those claims need a different coverage pathway entirely, or they'll deny.

The policy also cross-references Chapter 15 of the Medicare Benefit Policy Manual specifically for the fetal genetic disorders indication. That cross-reference isn't decorative — it means the benefit category and coverage criteria for prenatal cytogenetics have additional governing language that NCD 198 alone doesn't capture. Pull that chapter before you bill maternal-fetal medicine cases under this NCD.

CMS Cytogenetic Studies Billing Guidelines and Action Items 2026

The absence of specific CPT or HCPCS codes in NCD 198 doesn't simplify your work — it shifts the burden to diagnosis and documentation. Here's what to do before claims dated March 7, 2026 and later hit your clearinghouse.

CPT, HCPCS, and ICD-10 Codes for Cytogenetic Studies Under NCD 198

The current version of NCD 198 does not list specific CPT, HCPCS, or ICD-10 codes in the policy document. This is worth flagging directly because it affects how you validate claims.

What This Means for Your Coding Team

Without a code list embedded in the NCD, your coders and billing staff are working off the clinical indications described in the policy rather than a discrete code set. The covered indications — fetal genetic disorders, failure of sexual development, chronic myelogenous leukemia, acute leukemias (FAB L1–L3 and M0–M7), and myelodysplasia — need to be supported by diagnosis codes on the claim, but NCD 198 itself doesn't enumerate which ICD-10-CM codes qualify.

That gap creates real exposure. Different coders may map the same clinical scenario differently, and without explicit code-level guidance in the NCD, claim adjudication can vary by MAC (Medicare Administrative Contractor). Check with your MAC's local coverage policies and any applicable LCDs that may operate alongside NCD 198 — there may be code-level guidance at the local level that NCD 198 defers to.

If you're not sure how the lack of a code list affects your specific claim mix or MAC jurisdiction, loop in your billing consultant before submitting high-volume cytogenetic claims under the March 7, 2026 version of this policy.