81507 Genetic testing

CPT 81507

CPT 81507: Assay-Specific Cell-Free DNA ScreeningAssay-Specific Cell-Free DNA Screening

The short answer

81507 describes cell-free DNA screening for the common fetal trisomies (21, 18, and 13) performed by one laboratory's specific proprietary method. Clinically it is the same NIPT service as 81420; the code differs because it is assigned to a particular assay rather than to the service category. The performing lab bills it, and a lab reports 81507 or 81420, never both.

Source: ACOGSource: SMFMSource: CMS

When to use 81507

The ordering practice never chooses between 81507 and 81420; the lab does, based on which assay it runs and which code it holds. What the practice should know is that the two codes are interchangeable at the policy level: prior-auth requirements, coverage criteria, and denial patterns track the service, not the code number. If a payer's NIPT policy lists 81420, it almost always lists 81507 in the same paragraph. The practice-side work is identical: indication, diagnosis code, prior auth, counseling.

81507 vs 81420

81507 · Assay-specific code

Assigned to one lab's specific cfDNA analysis method
Only labs running that assay report it
Screens the same three trisomies
Coverage criteria mirror 81420 on nearly every policy

81420 · Generic panel code

Available to any lab performing multi-chromosome cfDNA screening
The code most payer policies are written against
The better search term when checking a coverage policy
Same prior-auth and documentation burden

Documentation checklist

Documentation lives on the practice side even though the claim goes out under the lab's NPI. The record that supports an 81507 claim is the same record that supports 81420.

✓ Order naming the test and the screening indication

✓ Gestational age of 10 weeks or later at the draw

✓ Diagnosis code reflecting actual risk status, not a reflexive high-risk code

✓ Prior authorization obtained under whichever code the lab will bill

✓ Pre-test counseling documented: screening, not diagnostic

✓ Patient cost or ABN conversation when the plan's coverage is unclear

Global package rules

Like all prenatal lab work, this screen sits outside the global OB package and never touches the 59400 claim. It is a clinical laboratory service priced on the Clinical Laboratory Fee Schedule rather than the Medicare Physician Fee Schedule, so no MPFS fee table appears on this page. One practical wrinkle unique to assay-specific codes: if the practice obtains prior authorization under 81420 but the lab bills 81507, some payers treat the auth as mismatched. Confirm with the lab which code it reports before requesting the auth. CMS

Common denials

CO-197 Authorization does not match the billed code

Why it happens

Prior auth was issued for 81420 but the lab billed 81507, or no auth was obtained at all.

How to fix

Ask the lab which code it bills before requesting authorization, and request the auth under that code. For a mismatch denial, most payers will amend the existing auth on appeal since the service is the same.

Source: CMS

CO-50 Not medically necessary for the diagnosis billed

Why it happens

The plan restricts cfDNA screening to high-risk pregnancies and the claim carried an average-risk code.

How to fix

Code any legitimate high-risk indication that exists in the record. For truly average-risk patients, appeal with the ACOG/SMFM position that cfDNA screening be offered to all pregnant patients.

Source: ACOG

CO-96 Code not on the plan's coverage list

Why it happens

Older or narrower policies sometimes list only the generic panel code and reject the assay-specific one as unlisted.

How to fix

Appeal with the policy itself, pointing out the assay-specific code describes the identical covered service. Payers usually process these as coding-equivalence appeals rather than medical-necessity appeals.

Source: CMS

CO-B7 Lab not enrolled or out of network

Why it happens

Assay-specific codes are tied to specific labs, so if that lab is out of network there is no in-network way to bill the same code.

How to fix

For future orders, check network status before the draw; an in-network lab running a different assay will bill 81420 or its own code. For the denied claim, ask the lab about self-pay caps before balance-billing the patient.

Source: CMS

FAQ

What is the CPT code description for 81507?

In plain language, 81507 covers a blood-based screen that analyzes cell-free fetal DNA in maternal plasma for trisomies 21, 18, and 13, performed using one specific laboratory's proprietary sequencing and analysis method.

Why do some labs bill 81507 instead of 81420?

Certain codes are granted for specific proprietary assays. A lab running that particular method reports its assay-specific code; labs running other methods use the generic 81420. The clinical service the patient receives is the same category of screening.

Does the practice do anything differently when the lab uses 81507?

Only one thing: get the prior authorization under the code the lab will actually bill. Everything else, indication, diagnosis coding, counseling, cost conversation, is identical to any NIPT order.

Can 81507 and 81420 appear on the same claim?

No. They describe the same screening event through different code pathways. One test, one code, one claim line.

Is coverage different for 81507 than for 81420?

Rarely. Nearly all payer NIPT policies list both codes with identical criteria. The occasional exception is an outdated policy listing only one code, which is appealable as a coding-equivalence issue.

CPT® is a registered trademark of the American Medical Association. Educational reference only, not billing, legal, or medical advice. Maintained by Ouma Health, a maternal-fetal telemedicine practice. Printed from obcodingguide.com, content current as of July 2026.