TL;DR: The Centers for Medicare & Medicaid Services modified NCD 204, its coverage policy governing obsolete and unreliable diagnostic tests, effective March 7, 2026. Here's what billing teams need to know before submitting claims for any of the affected tests.
CMS's National Coverage Determination 204 covers a specific list of diagnostic tests that Medicare considers either obsolete or of insufficient clinical value to warrant routine reimbursement. The policy draws a hard line: these tests don't get paid unless the ordering physician documents satisfactory medical justification. No specific CPT or HCPCS codes are listed in the current policy document, which creates its own set of billing challenges—more on that below.
Quick-Reference Table
| Field | Detail |
|---|---|
| Payer | CMS (Centers for Medicare & Medicaid Services) |
| Policy | Obsolete or Unreliable Diagnostic Tests |
| Policy Code | NCD 204 |
| Change Type | Modified |
| Effective Date | 2026-03-07 |
| Impact Level | Medium |
| Specialties Affected | Internal medicine, gastroenterology, cardiology, pathology, laboratory medicine, hematology |
| Key Action | Audit your lab and diagnostic charge capture for any of the 30+ listed tests; ensure physician-level medical necessity documentation exists before billing Medicare |
CMS Obsolete Diagnostic Test Coverage Criteria and Medical Necessity Requirements 2026
NCD 204 is the National Coverage Determination that governs Medicare's coverage policy for diagnostic tests CMS has classified as either obsolete or outmoded. The policy splits into two categories: general diagnostic tests and cardiovascular tests. Both categories operate under the same basic rule—Medicare will not routinely pay for these tests.
The word "routinely" is doing a lot of work in that sentence. CMS isn't saying these tests are never covered. It's saying they require affirmative medical necessity justification from the performing physician before a claim will be reimbursed. That's a meaningful distinction if your billing team is assuming denial by default and not bothering to submit with documentation.
When a claim for one of these tests is subject to Quality Improvement Organization review, the QIO determines whether medical justification is satisfactory. When a claim isn't subject to QIO review, that determination falls to the A/B Medicare Administrative Contractor for your jurisdiction. Know which MAC covers your region—they don't all interpret "satisfactory medical justification" identically.
The real issue here is documentation at the point of order. If the physician doesn't record why a guanase blood test or a Rehfuss gastric acidity test was medically necessary for this specific patient, you're not getting paid. A generic diagnosis code attached to the claim isn't enough.
CMS NCD 204 Exclusions and Non-Covered Indications
Section A: General Diagnostic Tests
The following tests are classified as obsolete under NCD 204 and will not receive routine Medicare reimbursement:
| # | Excluded Procedure |
|---|---|
| 1 | Amylase, blood isoenzymes, electrophoretic |
| 2 | Chromium, blood |
| 3 | Guanase, blood |
| 4 | Zinc sulphate turbidity, blood |
| 5 | Skin test, cat scratch fever |
| 6 | Skin test, lymphopathia venereum |
| 7 | Circulation time, one test |
| 8 | Cephalin flocculation |
| 9 | Congo red, blood |
| 10 | Hormones, adrenocorticotropin quantitative animal tests |
| 11 | Hormones, adrenocorticotropin quantitative bioassay |
| 12 | Thymol turbidity, blood |
| 13 | Skin test, actinomycosis |
| 14 | Skin test, brucellosis |
| 15 | Skin test, psittacosis |
| 16 | Skin test, trichinosis |
| 17 | Calcium, feces, 24-hour quantitative |
| 18 | Starch, feces, screening |
| 19 | Chymotrypsin, duodenal contents |
| 20 | Gastric analysis, pepsin |
| 21 | Gastric analysis, tubeless |
| 22 | Calcium saturation clotting time |
| 23 | Capillary fragility test (Rumpel-Leede) |
| 24 | Colloidal gold |
| 25 | Bendien's test for cancer and tuberculosis |
| 26 | Bolen's test for cancer |
| 27 | Rehfuss test for gastric acidity |
| 28 | Serum seromucoid assay for cancer and other diseases |
These tests span laboratory chemistry, immunology, fecal analysis, and gastric testing. Most are genuinely archaic—the Rumpel-Leede capillary fragility test and Congo red assay, for example, have been out of routine clinical practice for decades. If you're seeing any of these ordered in your facility, that's a conversation worth having with your medical director, not just your billing team.
Section B: Cardiovascular Tests — Phonocardiography and Vectorcardiography
CMS separately designates the following cardiovascular tests as outmoded and of little clinical value. These receive no routine Medicare reimbursement regardless of documentation:
| # | Excluded Procedure |
|---|---|
| 1 | Phonocardiogram with or without ECG lead, with supervision during recording, interpretation and report (equipment supplied by physician) |
| 2 | Phonocardiogram, tracing only, without interpretation and report (equipment supplied by hospital or clinic) |
| 3 | Phonocardiogram, interpretation and report only |
| 4 | Phonocardiogram with ECG lead, with indirect carotid artery and/or jugular vein tracing, and/or apex cardiogram, with interpretation and report |
| 5 | Phonocardiogram, without interpretation and report |
| 6 | Phonocardiogram, interpretation and report only (stand-alone) |
| 7 | Intracardiac phonocardiogram |
| 8 | Vectorcardiogram (VCG), with or without ECG, with interpretation and report |
| 9 | Vectorcardiogram, tracing only, without interpretation and report |
| 10 | Vectorcardiogram, interpretation and report only |
Phonocardiography and vectorcardiography were largely replaced by echocardiography and advanced ECG analysis. If a cardiologist in your practice is still ordering VCGs or phonocardiograms, confirm whether they're aware these are non-covered under Medicare's coverage policy.
Coverage Indications at a Glance
| Indication / Test Category | Coverage Status | Relevant Codes | Notes |
|---|---|---|---|
| General diagnostic tests listed in Section A (obsolete) | Not routinely covered | No specific CPT/HCPCS codes listed in NCD 204 | May be covered with physician-documented medical necessity; subject to QIO or MAC review |
| Phonocardiography (all variants listed in Section B) | Not covered | No specific CPT/HCPCS codes listed in NCD 204 | Outmoded; no medical necessity exception documented in policy |
| Vectorcardiography (all variants listed in Section B) | Not covered | No specific CPT/HCPCS codes listed in NCD 204 | Outmoded; no medical necessity exception documented in policy |
| Section A tests with documented physician justification | Conditionally covered | No specific CPT/HCPCS codes listed in NCD 204 | Physician must document why test was medically necessary for this patient; MAC or QIO makes final determination |
CMS Obsolete Diagnostic Test Billing Guidelines and Action Items 2026
| # | Action Item |
|---|---|
| 1 | Audit your lab and diagnostic order history before March 7, 2026. Pull claims from the last 12 months and identify any of the Section A or Section B tests. If you're billing these to Medicare, document how often and under what circumstances. This tells you your actual exposure. |
| 2 | Build a physician documentation protocol for Section A exceptions. Since Section A tests can be covered with sufficient justification, create a simple attestation or addendum template physicians can attach to orders. The MAC or QIO will want to see why this specific patient needed a test like guanase or zinc sulphate turbidity—not just a diagnosis code. |
| 3 | Treat Section B tests as categorically non-covered for Medicare. Unlike Section A, phonocardiography and vectorcardiography have no documented exception pathway in NCD 204. Don't waste documentation time on these. If your cardiologists are ordering them, redirect to covered alternatives and update your order sets accordingly. |
| 4 | Contact your MAC now about their documentation standards. CMS delegates the "satisfactory medical justification" determination to A/B MACs when QIO review doesn't apply. Different MACs have different thresholds. Call or check your MAC's LCD database before March 7, 2026 so your billing team isn't guessing at claim submission. |
| 5 | Flag the missing CPT/HCPCS codes as a compliance gap. NCD 204 does not list specific codes in the current policy document. That's genuinely unusual for a coverage policy of this scope, and it creates a real billing challenge—your coding team needs to know which CPT or HCPCS codes map to these test descriptions. Work with your coding consultant or compliance officer to identify the correct codes for any tests you're actively billing, and document that mapping. If you're unsure how to handle the code gap, loop in your compliance officer before submitting claims after March 7, 2026. |
| 6 | Update your charge description master (CDM) to flag these tests. Add an internal review flag for any CDM line items that correspond to the 30+ tests in NCD 204. This catches orders before they become claims, not after they become denials. |
| Previous Version | Current Version |
|---|---|
| Coverage is considered experimental and investigational for all indications | Coverage is considered medically necessary when specific criteria are met |
| Prior authorization is not required | Prior authorization is required for initial treatment |
| Documentation must include clinical history | Documentation must include clinical history |
| Re-review every 24 months | Re-review every 12 months with updated clinical documentation |
CPT, HCPCS, and ICD-10 Codes for Obsolete Diagnostic Tests Under NCD 204
The policy document for NCD 204 does not include specific CPT, HCPCS Level II, or ICD-10-CM codes. This is a significant billing consideration.
Without enumerated codes in the NCD itself, your coding team has to map the test descriptions in the policy to the appropriate CPT codes independently—and those mappings need to hold up to MAC scrutiny if a claim is reviewed. This isn't optional. If you bill any of the Section A tests to Medicare and a claim is pulled for review, you need to be able to show both the code and the documentation.
Work with a certified medical coder and, if necessary, your compliance officer to establish these mappings before March 7, 2026. The absence of codes in the NCD doesn't mean the policy doesn't apply—it means your internal coding accuracy becomes the only defense against a claim denial or a take-back.
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