81420 Genetic testing

CPT 81420

CPT 81420: NIPT Cell-Free DNA Aneuploidy ScreeningNIPT Cell-Free DNA Aneuploidy Screening

The short answer

81420 is the panel code for noninvasive prenatal testing (NIPT): sequencing cell-free fetal DNA from a maternal blood draw to screen for the common chromosome count abnormalities (trisomy 21, 18, and 13). The performing laboratory bills it, not the OB practice, but the practice's order, diagnosis code, and prior authorization decide whether it pays.

Source: ACOGSource: SMFMSource: CMS

When to use 81420

81420 applies when a lab runs a multi-chromosome cell-free DNA screen on maternal plasma, generally from 10 weeks gestation onward. The OB practice's job is upstream: document the indication, pick the diagnosis code that matches the patient's risk status, obtain prior authorization when the payer requires it, and send a clean order. The lab submits the claim. If the lab uses its own assay-specific code instead, see 81507; the practice-side workflow is the same.

81420 vs the proprietary-assay route

81420 · Panel code

Generic code any lab can report for multi-chromosome cfDNA screening
Covers the standard trisomy 21/18/13 screen
Most payer NIPT policies are written against this code
Prior-auth rules attach here for most plans

81507 · Assay-specific code

Tied to one laboratory's specific cfDNA method
Reported instead of 81420, never alongside it
Same clinical service from the practice's point of view
Payer policies usually list both codes together

Documentation checklist

NIPT denials are almost never about the lab work. They are about what the ordering practice did or did not put in the record before the blood draw.

✓ Order with the screening indication and gestational age (10 weeks or later)

✓ Diagnosis code matching the patient's actual risk status (advanced maternal age, prior aneuploidy, abnormal serum screen, or average-risk supervision-of-pregnancy code)

✓ Prior authorization number when the payer requires one, captured before the draw

✓ Pre-test counseling note: screening test, not diagnostic, positive results need confirmation

✓ Patient cost conversation or ABN when coverage is uncertain

✓ Single-gestation vs multiple-gestation status, since some payers restrict coverage for multiples

Global package rules

NIPT sits entirely outside the global OB package. The lab bills 81420 on its own claim; nothing about it touches 59400. Two practice-side notes: first, this is a clinical laboratory service priced on the Clinical Laboratory Fee Schedule, not the Medicare Physician Fee Schedule, so there is no MPFS fee table on this page. Second, coverage history matters: payers originally limited NIPT to high-risk pregnancies, and after ACOG and SMFM endorsed offering cfDNA screening to all patients in 2020, most (not all) commercial policies extended coverage to average-risk pregnancies. A handful of plans also require the lab to report a Z-identifier from a test registry (the DEX registry model used by some Medicaid programs and MolDX-following payers) before the claim will process. ACOG

Common denials

CO-197 No prior authorization on file

Why it happens

The payer requires precertification for molecular pathology codes and none was obtained before the draw. This is the single most common NIPT denial driver.

How to fix

Build prior auth into the ordering workflow, not the billing workflow. If the claim already denied, request a retro authorization with the order date and indication; many payers allow a short retro window.

Source: CMS

CO-50 Not medically necessary for average risk

Why it happens

The plan's policy still limits NIPT to high-risk indications and the claim carried an average-risk pregnancy diagnosis.

How to fix

Check whether a high-risk indication actually exists and was just not coded (age 35 or older at delivery, abnormal serum screen, prior affected pregnancy). If the patient is genuinely average risk, appeal citing the ACOG/SMFM guidance that cfDNA screening be offered to all pregnant patients, and confirm the plan's current policy year; many updated after 2020.

Source: ACOG

CO-16 Claim lacks required identifier

Why it happens

The payer requires a test-registry Z-code alongside 81420 and the lab's claim did not carry it.

How to fix

This one is the lab's to fix: the lab registers the assay and resubmits with the Z-identifier. The practice's role is picking a lab that has done that registration for the patient's plan.

Source: CMS

CO-96 Non-covered service under the plan

Why it happens

Some plans, especially self-funded employer plans, exclude NIPT for average-risk pregnancies entirely regardless of medical necessity arguments.

How to fix

Verify the exclusion in the plan document, then move the balance to the patient consistent with the pre-draw cost conversation. Many labs have capped self-pay rates; point the patient there.

Source: CMS

CO-B7 Provider not certified for this service

Why it happens

The performing lab is out of network or not enrolled with the payer for molecular pathology.

How to fix

Redirect future orders to the payer's in-network lab. For the denied claim, ask the lab about its out-of-network patient protection policies before the balance reaches the patient.

Source: CMS

FAQ

What is the CPT code description for 81420?

In plain language, 81420 covers a laboratory analysis of cell-free fetal DNA circulating in the mother's blood, screening several chromosomes at once for count abnormalities, principally trisomy 21 (Down syndrome), trisomy 18, and trisomy 13.

Does the OB practice bill 81420?

No. The performing laboratory bills it. The practice bills only for its own services (the blood draw if done in office, and any distinct counseling visit). The practice's order and diagnosis code still drive whether the lab's claim pays.

Is NIPT covered for average-risk pregnancies?

Increasingly yes. ACOG and SMFM recommend offering cfDNA screening to all pregnant patients, and most commercial payers and state Medicaid programs now cover average-risk screening. A minority of plans still restrict it to high-risk indications, so verify per plan.

Why did the claim need a Z-code?

Some payers, mostly those following the MolDX program model, require molecular tests to be registered in a test registry and billed with the assigned Z-identifier so the payer knows exactly which assay ran. The lab handles registration; a missing Z-code is a lab-side rejection.

What is the difference between 81420 and 81507?

Both describe cfDNA aneuploidy screening. 81420 is the generic panel code any lab can use; 81507 is tied to one specific laboratory method. A lab reports one or the other, never both, and payer policies generally treat them the same way.

Can NIPT and serum screening both be billed in the same pregnancy?

Payers generally cover one screening approach per pregnancy. If a serum screen already resulted and NIPT follows an abnormal result, code the abnormal finding as the indication. Ordering both up front invites a denial on the second claim.

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.