Hypoxic Ischemic Encephalopathy — CPB 0812 | AETNA Coverage Update

Aetna modified CPB 0812 for hypoxic ischemic encephalopathy (HIE), effective November 22, 2025. Here's what billing teams need to do.

Aetna, a CVS Health company, updated its HIE coverage policy under CPB 0812 in the Aetna therapeutic hypothermia coverage policy. The update clarifies which interventions meet medical necessity — and, critically, which ones don't. CPT 99184 (initiation of selective head or total body hypothermia in critically ill neonates) remains the covered procedure. A wide range of adjunctive therapies, biomarkers, and diagnostic approaches now carry an explicit experimental designation, with codes ranging from CPT 97810–97814 (acupuncture) to HCPCS J0885 and J0887 (erythropoietin injections) all landing in the non-covered column.

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Quick-Reference Table

Field	Detail Copy
Payer	Aetna, a CVS Health company
Policy	Hypoxic Ischemic Encephalopathy
Policy Code	CPB 0812
Change Type	Modified
Effective Date	November 22, 2025
Impact Level	Medium
Specialties Affected	Neonatology, NICU billing, pediatric neurology, laboratory
Key Action	Review all HIE-related charge capture and confirm that only CPT 99184 is submitted for therapeutic hypothermia; flag adjunctive therapies and biomarker codes for denial risk

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Aetna HIE Coverage Criteria and Medical Necessity Requirements 2025

The CPB 0812 Aetna system designates exactly one category of treatment as medically necessary for HIE: therapeutic hypothermia (TH), delivered as either total body cooling (TBC) or selective head cooling (SHC).

Aetna covers TBC and SHC for neonates 28 days of age or younger with moderate or severe HIE. The ICD-10-CM diagnosis codes that trigger this coverage are P91.62 (moderate HIE) and P91.63 (severe HIE). P96.0 (congenital renal failure) is also listed in the context of neonates with HIE who receive therapeutic hypothermia.

CPT 99184 — initiation of selective head or total body hypothermia in the critically ill neonate — is the billing code covered when these criteria are met. Your team should confirm that P91.62 or P91.63 appears on every claim billed with 99184.

The policy includes a clinical timing note that matters for documentation: therapeutic hypothermia must be administered within six hours of birth to be appropriate for high-risk term neonates. It may not be effective when the placenta shows evidence of chorioamnionitis with fetal vasculitis and chorionic plate meconium. While Aetna doesn't explicitly deny coverage based on this note, it creates a documentation requirement. Make sure the medical record supports the six-hour window.

Prior authorization requirements are not explicitly called out in this coverage policy, but don't skip that step. NICU procedures at this acuity level routinely require prior auth under most commercial plans. Verify with your Aetna representative before assuming prior authorization isn't needed.

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Aetna HIE Exclusions and Non-Covered Indications

This is where CPB 0812 gets detailed — and where your denial risk lives.

Aetna now explicitly designates more than 20 adjunctive therapies as experimental, investigational, or unproven for HIE treatment. This list includes things your NICU team may already be using or studying: erythropoietin (HCPCS J0885, J0887, J0881, J0882, Q4081), magnesium sulfate (J3475), allopurinol (J0206), cyclosporine (J7502, J7515, J7516), N-acetylcysteine (J7604), and adenosinergic agents (J0153). All of them — not covered.

Stem cell therapy is also experimental under this policy. That designation pulls in a large block of CPT codes: 38204 through 38215, 38230, 38240, 38241, and 38242. If your team is billing any bone marrow or stem cell procedures in the context of an HIE admission, expect those claims to deny.

Acupuncture for HIE — CPT 97810, 97811, 97812, 97813, and 97814 — is also explicitly excluded. This won't affect most NICU billing teams, but if you're in a system that offers integrative therapies for neonatal care, flag it now.

Biomarker testing is the other major exclusion category. Aetna does not cover a long list of biomarkers used for HIE diagnosis or outcome prediction. That includes CPT 0548U (GFAP, chemiluminescent immunoassay), CPT 82552 (creatine kinase isoenzymes for CK-BB), CPT 83529 (interleukin-6), and CPT 86316 (neuron-specific enolase). Sex steroid hormone panels are also excluded — codes 82154, 82157, 82160, 82626, 82627, 82642, 82670, 82671, 82672, 82677, 82679, 82681, 83498, 84140, 84143, 84144, 84233, 84234, 84402, 84403, and 84410 all land in the non-covered column when used as HIE biomarkers.

Cerebral near-infrared spectroscopy (cerebral NIRS) for monitoring neonatal HIE is also experimental. No specific CPT code is listed for this in the policy, but if you're billing NIRS monitoring in this context, that claim is at risk.

The real issue here is that research institutions and academic medical centers are actively studying many of these interventions. Your clinical team may be using them. Your billing team may be submitting them. The Aetna coverage policy says none of them are reimbursable for HIE — full stop.

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Coverage Indications at a Glance

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Aetna HIE Billing Guidelines and Action Items 2025

The effective date is November 22, 2025. If you haven't acted on this yet, do it now.

Copy Action Items

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CPT, HCPCS, and ICD-10 Codes for HIE Under CPB 0812

Covered CPT Codes (When Selection Criteria Are Met)

Code	Type	Description Copy
99184	CPT	Initiation of selective head or total body hypothermia in the critically ill neonate, includes appropriate patient selection by review of clinical, imaging, and laboratory data

Not Covered / Experimental CPT Codes

Other CPT Codes Referenced in CPB 0812

Not Covered / Experimental HCPCS Codes

Key ICD-10-CM Diagnosis Codes

Code	Description Copy
P91.62	Moderate hypoxic ischemic encephalopathy [HIE]
P91.63	Severe hypoxic ischemic encephalopathy [HIE]
P96.0	Congenital renal failure [in context of HIE receiving therapeutic hypothermia]

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