ADAMTS13 Assay for Thrombotic Thrombocytopenic Purpura (TTP) — CPB 0780 | AETNA Coverage Update

TL;DR: Aetna modified CPB 0780 governing ADAMTS13 assay coverage, effective November 15, 2025. The change updates which indications qualify for reimbursement under CPT 85397 — and the exclusion list is long.

Aetna's ADAMTS13 assay coverage policy under CPB 0780 draws a hard line: CPT 85397 is covered for one thing — prognostic assessment in confirmed thrombotic thrombocytopenic purpura (TTP). Everything else, and we mean a striking 46+ indications, lands in experimental or investigational territory. If your team bills CPT 85397 for any other diagnosis, expect a claim denial. This update codifies that boundary in detail.

Quick-Reference Table

Aetna ADAMTS13 Assay Coverage Criteria and Medical Necessity Requirements 2025

The Aetna ADAMTS13 assay coverage policy is narrow by design. Aetna considers CPT 85397 — the functional activity assay for ADAMTS13 — medically necessary in exactly one clinical context: assessing prognosis in persons with thrombotic thrombocytopenic purpura (TTP).

That's it. One indication. One covered use.

Medical necessity under this coverage policy requires that the patient has thrombotic thrombocytopenic purpura (TTP). Consult the full CPB 0780 policy document for the confirmed ICD-10 codes that support medical necessity for CPT 85397 — do not rely on inferred code ranges for billing decisions.

This policy does not address prior authorization requirements. Consult Aetna's authorization schedules separately. Talk to your compliance officer if your practice sees mixed TTP and non-TTP volume, because the line between "assessment" and "monitoring" can get blurry in complex cases.

Aetna ADAMTS13 Assay Exclusions and Non-Covered Indications

This is where the policy gets detailed — and where your billing team needs to pay attention before November 15, 2025.

Aetna explicitly classifies ADAMTS13 assay as experimental, investigational, or unproven for 46 separate indications. That list includes conditions you might reasonably expect a clinician to order this test for. COVID-19 biomarker monitoring, sepsis-associated thrombotic microangiopathy, hemolytic uremic syndrome (HUS) — all non-covered.

A few entries on this list stand out as claim-denial risks because they're clinically adjacent to TTP. HUS and TTP share overlapping features. Sepsis-associated thrombotic microangiopathy involves the same coagulation pathways. Disseminated intravascular coagulation (DIC) is another one where a clinician might reach for this assay. None of these are covered under CPB 0780.

ADAMTS13 mutation testing for non-cirrhotic portal hypertension is also explicitly non-covered — a separate, specific call-out from Aetna. If your hepatology or gastroenterology teams are ordering mutation testing alongside the functional assay, flag that. The mutation testing piece has no covered indication under this policy.

The real issue here is documentation. A claim for CPT 85397 paired with a sepsis code (A41.9) will deny. Same with HUS. Same with any of the COVID-19-related codes. The diagnosis code on the claim must support TTP prognosis assessment — or the claim will not pass Aetna's medical necessity review. Consult the full CPB 0780 policy for the confirmed covered ICD-10 codes before submitting.

Coverage Indications at a Glance

Aetna ADAMTS13 Assay Billing Guidelines and Action Items 2025

Here's what your billing team needs to do before November 15, 2025.

1. Audit your CPT 85397 charge capture now.
Pull all CPT 85397 claims from the past 12 months billed to Aetna. Flag any that don't pair with a TTP diagnosis code. Those are your denial risk cases going forward. Consult the full CPB 0780 policy for the confirmed covered ICD-10 codes before your audit.

2. Update your ICD-10 mapping for CPT 85397.
Your charge capture system should flag CPT 85397 as requiring a TTP diagnosis code for Aetna. Any other primary diagnosis should trigger a billing hold or review. This is where a mismatch between the ordering clinician's intent and the biller's code selection creates exposure.

3. Educate ordering clinicians on covered vs. non-covered indications.
Hematologists are the primary users here, but nephrologists, neurologists, and intensivists also order ADAMTS13 testing. Send them a one-page reference showing exactly what Aetna covers under CPB 0780. The HUS and sepsis-associated TMA exclusions will surprise some providers.

4. Review open appeals for denied CPT 85397 claims.
If you have claims denied for ADAMTS13 testing in non-TTP contexts, this policy update won't help you recoup them — it confirms Aetna's position. Close those appeals or redirect them appropriately rather than investing more time.

5. Check for allogeneic HSCT billing combinations.
The policy lists chemotherapy administration codes (CPT 96413, 96415, 96416, 96417) and transplant codes (CPT 38204–38215, 38240) as "related" codes under CPB 0780. These are not covered codes for ADAMTS13 — they appear as context. Don't add CPT 85397 to HSCT billing packages expecting separate reimbursement. That's a different policy question entirely, and you should confirm with your compliance officer how these intersect with your transplant billing protocols.

6. Watch for the effective date in Aetna's system.
The effective date of November 15, 2025 is the date Aetna's systems reflect this modified coverage policy. Submit claims for dates of service on or after November 15 under the updated criteria. Claims for dates of service before that date follow the prior policy version — keep that distinction clean in your records.

CPT, HCPCS, and ICD-10 Codes for ADAMTS13 Assay Under CPB 0780

Covered CPT Codes (When Selection Criteria Are Met)

Other CPT Codes Related to CPB 0780

These codes are referenced in the policy as context. They are not independently covered for ADAMTS13 testing.

Key ICD-10-CM Diagnosis Codes

The policy references 509 ICD-10 codes across covered and non-covered indications. The codes below represent the most billing-relevant entries from the non-covered group confirmed in the source data. For the complete list of covered ICD-10 codes supporting TTP prognosis assessment under CPT 85397, consult the full CPB 0780 policy document directly — do not rely on inferred ranges for claim submission.

The full ICD-10 list in the policy runs to 509 codes — nearly all of them in the non-covered/experimental group. The takeaway is simple: if it's not TTP prognosis assessment, CPT 85397 does not have a covered indication under Aetna CPB 0780. Pull the full policy document to confirm the exact covered ICD-10 codes before updating your charge capture.