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EDI 278—formally designated as the ASC X12N 278 Health Care Services Review — Request for Review and Response (Version 005010X217)—is the federally mandated HIPAA Electronic Data Interchange transaction standard (codified at 45 CFR § 162.1302) governing electronic prior authorization requests, specialist referrals, inpatient admission notifications, and utilization review responses between healthcare providers and health plans. Within the broader EDI in healthcare stack, `X12 278` pairs with `X12 275` (Additional Information to Support a Health Care Services Review) and modern prior authorization software implementing the HL7 FHIR Da Vinci Prior Authorization Support (PAS) Implementation Guide.
What Is EDI 278? Regulatory Mandate (45 CFR § 162.1302) and Request/Response Architecture
Under the Health Insurance Portability and Accountability Act (HIPAA) Administrative Simplification provisions (45 CFR Part 162, Subpart M, § 162.1301–162.1302), all HIPAA-covered entities—health plans, medical claims clearinghouses, and healthcare providers conducting electronic transactions—must use the ASC X12 Technical Report Type 3 (TR3) implementation specification `005010X217` (and its adopted Errata `005010X217E1`, `E2`, and `E3`) for five categories of referral certification and authorization:
- Prior Authorization / Precertification (`UM01 = HS` or `AR` / `SC`): Requesting payer medical-necessity approval before performing an elective surgical procedure, advanced diagnostic imaging study (MRI, CT, PET), specialty pharmaceutical infusion, or Durable Medical Equipment (DME) dispensing.
- Specialist Referral (`UM01 = RF`): Primary care provider (PCP) authorization for a beneficiary in a gated Health Maintenance Organization (HMO) or Point-of-Service (POS) plan to consult an in-network or out-of-network specialist.
- Inpatient Admission & Concurrent Review (`UM01 = AR` / `IN`): Acute care hospital notification of inpatient admission and continued-stay length-of-stay (LOS) certification.
- Home Health & Post-Acute Care Certification: Authorization of Skilled Nursing Facility (SNF), Inpatient Rehabilitation Facility (IRF), or home health episodes.
- Status Inquiry & Cancellation/Modification: Querying an existing authorization number (`REF*BB`) or updating approved service dates/units.
Single Transaction ID (`ST*278`) for Both Request and Response
Unlike eligibility (`270` Request / `271` Response) or claims (`837` Claim / `835` Remittance), prior authorization uses the same transaction set identifier (`278`) for both the provider’s outbound request and the payer’s inbound response. An X12 parser distinguishes the direction by inspecting the `BHT` (Beginning of Hierarchical Transaction) segment’s second element (`BHT02` — Transaction Set Purpose Code):
- `BHT*0007*13*…` (`BHT02 = 13`): Request (Provider or EHR/Clearinghouse $to$ Payer / Utilization Management Organization).
- `BHT*0007*11*…` (`BHT02 = 11`): Response (Payer / Utilization Management Organization $to$ Provider).
The 6 Hierarchical Loops (`HL`) and Key Segments of an X12 278 (`005010X217`) Transaction
Inside the `ST*278` / `SE` transaction envelope, data are organized into a strict 6-level parent-child tree using `HL` (Hierarchical Level) segments (`HL03` level codes `20`, `21`, `22`, `23`, `EV`, `SS`):
| Loop ID | HL03 Level Code |
Hierarchical Entity | Core X12 Segments & Clinical / Administrative Elements |
|---|---|---|---|
| Loop 2000A | 20 (Information Source) |
Utilization Management Organization (UMO) / Payer | `NM1*X3` (UMO Name & Payer ID), `PER` (UMO contact), `AAA` ( source-level request validation error) |
| Loop 2000B | 21 (Information Receiver) |
Requester (Ordering Provider / Clinic / Hospital) | `NM1*1P` or `FA` (Requester Name, Type 1/2 NPI in `NM109`), `REF`, `PRV` (Provider taxonomy code) |
| Loop 2000C | 22 (Subscriber) |
Insured Subscriber | `NM1*IL` (Subscriber Name & Member ID), `DMG` (DOB/Sex), `INS` |
| Loop 2000D | 23 (Dependent) |
Dependent Patient (Omitted if Subscriber is the Patient) | `NM1*QC` (Patient Name), `DMG` (Patient DOB/Sex), `INS` (Relationship code) |
| Loop 2000E | EV (Patient Event) |
Patient Care Event / Episode Header | `UM` (Health Care Services Review Info: category, certification type `I` Initial / `R` Renewal, place of service), `HI` (ICD-10-CM Diagnosis Codes `ABK`/`ABF`), `DTP` (Admission/Event dates), `CR1`/`CR2`/`CR5`/`CR6` (Ambulance/Chiropractic/Oxygen/Home Health clinical data), `PWK` (Attachment control numbers for `X12 275`), `HCR` (Event-level decision), `NM1*71`/`SJ` (Attending/Rendering Provider & Facility NPI) |
| Loop 2000F | SS (Service) |
Individual Procedure / Service Line | `SV1` (Professional CPT/HCPCS code, modifiers, requested units), `SV2` (Institutional Revenue Code & procedure), `SV3` (Dental), `DTP*472` (Service date), `PWK` (Service-level attachment link), `HCR` (Service-line approval/denial code & prior auth number) |
Decoding the Payer Response: `HCR` (Health Care Services Review) Action Codes
In an inbound `278 Response` (`BHT02 = 11`), the payer returns its utilization review determination in the `HCR` segment (at either the `2000E` Event level or `2000F` Service level):
- `HCR01 = A1` (Certified in Total): The requested procedure/admission is approved as submitted. `HCR02` (or `REF*BB`) returns the official **Prior Authorization / Certification Number** that must be populated into Loop `2300 REF*G1` on the downstream `EDI 837` claim.
- `HCR01 = A2` (Certified — Partial): Approved with modified units or length of stay (e.g., 3 inpatient days certified out of 5 requested).
- `HCR01 = A3` (Not Certified / Denied): Denied. `HCR03` carries the X12 Health Care Services Review Decision Reason Code explaining why medical necessity or benefit criteria were not met.
- `HCR01 = A4` (Pended): The request is pended awaiting clinical documentation (or manual medical director review). Accompanying `PWK` (Paperwork) and `MSG` segments specify which clinical notes or LOINC attachments must be transmitted via an unsolicited or solicited `ASC X12N 275` (`005010X210`) patient information transaction.
- `HCR01 = A6` (Modified) / `CT` (Contact Payer) / `NA` (No Action Required): `NA` indicates that the submitted CPT code does not require prior authorization under the member’s plan.
CAQH CORE Operating Rules for Prior Authorization (278) Infrastructure and Turnaround
To eliminate proprietary web-portal bottlenecks on top of the HIPAA `005010X217` syntax, the CAQH Committee on Operating Rules for Information Exchange (CAQH CORE) publishes the CAQH CORE Prior Authorization & Referrals (278) Operating Rules (Data Content, Infrastructure, and Connectivity Rules):
- Real-Time Response Turnaround (`≤ 20 Seconds`): When a provider submits a real-time `278 Request`, the health plan or UMO must return a `278 Response` (whether final `A1`/`A3`/`NA` auto-adjudication or `A4` pended acknowledgement with attachment instructions) within 20 seconds or less.
- Batch Processing Turnaround: Batch `278` requests submitted by 9:00 PM Eastern Time must return a batch `278 Response` by 7:00 AM Eastern Time on the next business day.
- Final Clinical Adjudication Timelines & CMS-0057-F Alignment: When a request is pended (`A4`) for clinical review, CAQH CORE rules and the federal CMS Interoperability and Prior Authorization Final Rule (CMS-0057-F) enforce strict decision clocks: under CMS-0057-F (effective 2026 for Medicare Advantage, Medicaid, CHIP, and FFE Qualified Health Plans), payers must issue final prior authorization decisions within 72 hours for expedited (urgent) requests and 7 calendar days for standard requests.
How EDI 278 Connects to HL7 FHIR Da Vinci PAS and Clinical Research Workflows
Because the ASC X12N 278 `005010X217` format remains mandated by HIPAA 45 CFR § 162.1302 unless an entity holds an approved HIPAA exception or bridges via a translator, modern EHR integrations use the HL7 Da Vinci Prior Authorization Support (PAS) Implementation Guide:
- FHIR `Claim/$submit` to X12 278 Translation: The clinician’s EHR constructs a FHIR R4 `Bundle` containing a `Claim` resource (`use = preauthorization`) and clinical C-CDA/FHIR attachments and sends it to `POST [base]/Claim/$submit`. An intermediary clearinghouse or payer gateway translates the FHIR `Claim` elements directly into `X12 278` Loops `2000A–2000F` (and `X12 275` attachments) and maps the payer’s `278 Response` (`HCR01`, `HCR02`) back into a FHIR `ClaimResponse`.
- Clinical Trial Qualifying Care Authorization: In oncology and cardiovascular clinical trials billed under CMS NCD 310.1, study coordinators submit `EDI 278` requests attaching the clinical trial protocol summary and NCT identifier (`X12 275`) so Medicare Advantage and commercial payers pre-certify standard-of-care PET/CT staging scans and concomitant hospital admissions prior to participant randomization.
Frequently Asked Questions
What is EDI 278?
EDI 278 (officially the ASC X12N 278 Health Care Services Review — Request for Review and Response, Version `005010X217`) is the HIPAA-mandated Electronic Data Interchange transaction standard under 45 CFR § 162.1302 used by healthcare providers and payers to submit and respond to prior authorization requests, specialist referrals, inpatient admission certifications, and concurrent/continued-stay utilization reviews.
How is EDI 278 used in clinical research and healthcare?
In healthcare revenue cycle and utilization management workflows, EHRs and clearinghouses transmit an EDI 278 Request (`BHT02 = 13`) to a health plan or Utilization Management Organization (UMO) and receive an EDI 278 Response (`BHT02 = 11`) carrying an `HCR` segment disposition (`A1` Certified in total, `A3` Denied, or `A4` Pended for clinical documentation via `X12 275`). In clinical trials, research access teams use EDI 278 transactions—and HL7 Da Vinci Prior Authorization Support (PAS) FHIR-to-278 translators—to obtain pre-service payer certification for standard-of-care imaging, oncology infusions, and surgical device implantations under CMS NCD 310.1.
Sources
- Electronic Code of Federal Regulations (eCFR). 45 CFR § 162.1302 — Standards for Referral Certification and Authorization (ASC X12N 278 005010X217).
- CAQH CORE. CAQH CORE Prior Authorization & Referrals (278) Operating Rules: Data Content, Infrastructure, and Connectivity.
- HL7 International. HL7 FHIR Da Vinci Prior Authorization Support (PAS) Implementation Guide (FHIR-to-X12 278 Mapping).
- Centers for Medicare & Medicaid Services (CMS). CMS Interoperability and Prior Authorization Final Rule (CMS-0057-F).
