Use 76821 for Doppler velocimetry of the fetal middle cerebral artery, most often the peak systolic velocity measurement used to surveil fetal anemia in alloimmunized pregnancies. It is a different vessel and a different code from umbilical artery Doppler 76820, and both can be reported at one visit when both are performed and documented.
Report 76821 when MCA waveforms are measured and interpreted. The classic indication is anemia surveillance: red cell alloimmunization, parvovirus exposure, or twin-twin transfusion evaluation, where the MCA peak systolic velocity predicts fetal anemia. The MCA is also interrogated in growth restriction to assess blood flow redistribution, typically alongside the umbilical study. This is MFM-territory imaging; most claims come from specialty practices, and payers expect the high-risk indication to be unmissable in the record.
Documentation checklist
MCA Doppler claims stand on the indication and the measured velocity. Both belong in the report, with the trend when the study is serial.
✓MCA waveform obtained at the proper angle and stored
✓Peak systolic velocity recorded, with multiples-of-the-median context for anemia surveillance
✓Pulsatility index where redistribution is the question
✓Comparison to prior studies in a surveillance series
✓Interpretation tied to management, such as timing of cordocentesis or transfusion
✓Signed report; separate findings if billed with same-day umbilical Doppler or growth scan
Global package rules
76821 is billed outside the global obstetric package, separate from 59400. It is separately reportable from 76820 at the same visit because the codes describe different vessels; document each waveform. Serial MCA studies, weekly is common in active anemia surveillance, are expected claims when the diagnosis supports them. NCCI
TC-26 components
Split the components when the interpreting physician does not own the equipment: 76821-26 for the professional read, 76821-TC for the technical side. Remote MFM interpretation of MCA studies is a common professional-component-only arrangement.
76821
Global: one entity owns equipment and interpretation
76821-26
Professional: interpretation only
76821-TC
Technical: equipment and technologist
Reimbursement
2026 · national Medicare averages
Component
Work RVU
Total RVU
2026 rate
76821Global
0.68
2.70
$90.18
76821-26Professional
0.68
1.00
$33.40
76821-TCTechnical
0.00
1.70
$56.78
National amounts under the 2026 Medicare Physician Fee Schedule (non-facility total RVU x $33.4009 conversion factor, no locality/MAC adjustment). Commercial and Medicaid rates differ. Verify current values with your MAC before billing.
Common denials
CO-50No qualifying indication
Why it happens
MCA Doppler was billed without a diagnosis supporting anemia surveillance or redistribution assessment.
How to fix
Link the alloimmunization, infection, TTTS, or growth restriction diagnosis. Routine MCA interrogation of a low-risk pregnancy is not covered.
Source: ACOG/SMFM
CO-97Bundled with same-day umbilical Doppler
Why it happens
The payer collapsed 76821 into 76820 billed the same visit.
How to fix
They are different vessels with separate waveforms and indices. Append the payer's distinct-service modifier where required and appeal with both measurements.
Source: NCCI
CO-151Serial studies exceeded frequency screen
Why it happens
Weekly anemia surveillance crossed the payer's utilization threshold.
How to fix
Appeal with the surveillance protocol and the MoM trend; weekly MCA-PSV is guideline-supported in active alloimmunization.
Source: ACOG/SMFM
N290Rendering provider not recognized
Why it happens
Some payers restrict fetal Doppler interpretation to credentialed specialists and the rendering NPI did not match.
How to fix
Confirm the interpreting physician's enrollment and specialty designation with the payer, then resubmit under the correct NPI.
Source: CMS
FAQ
What is the CPT code description for 76821?
In plain language, 76821 covers Doppler measurement of blood flow in the fetal middle cerebral artery, used mainly to detect fetal anemia through the peak systolic velocity, and in growth restriction to assess whether blood flow is redistributing to the brain.
Can 76820 and 76821 be billed at the same visit?
Yes, when both vessels are interrogated and each waveform is documented. They are separate codes for separate arteries; some payers want a distinct-service modifier on one line.
What indications support 76821?
Red cell alloimmunization, suspected fetal anemia from parvovirus or other causes, twin-twin transfusion evaluation, and redistribution assessment in growth restriction. The diagnosis must be on the claim.
How often is MCA Doppler billed in anemia surveillance?
Typically every one to two weeks while the risk is active, tracked as multiples of the median. Serial claims are normal; carry the diagnosis and trend documentation on each.
Is 76821 billed per fetus for twins?
When each fetus's MCA is separately studied, yes, on separate lines with modifier 59 on the additional fetus. Verify the payer's preferred format for multiple-gestation Doppler claims.
Is 76821 part of the global OB package?
No. Fetal Doppler studies are billed separately from 59400.
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.