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Medical necessity at the point of order

Payers ask whether an ordered study is justified for the documented clinical picture. ARKA checks ICD-10 indication against the ordered CPT at order entry — and surfaces a signal, not a final code.

Scope — flag and suggest, never assign

ARKA flags medical-necessity alignment for the ordering clinician and downstream coder. It does not assign billing codes, replace utilization review, or satisfy AUC/PAMA consultation requirements. The clinician retains full responsibility for the final order and documentation.

CPT descriptors on this page are illustrative. In production, CPT is displayed under AMA license; this demo uses synthetic policy rows only.

The pairing

CPT is what; ICD-10 is why

Medical necessity is the documented link between the clinical problem and the procedure billed.

CPT (procedure)

Current Procedural Terminology codes describe what was ordered — modality, body region, and contrast when applicable (e.g., MRI lumbar spine without contrast, CPT 72148).

ICD-10-CM (indication)

Diagnosis codes on the order explain why imaging is clinically appropriate (e.g., low back pain M54.5). Payers and Medicare contractors map allowed pairings in LCDs, NCDs, and commercial medical policies.

When indication and procedure diverge from published policy tables, claims face medical necessity denials — often before appropriateness is ever questioned clinically.

Policy layer

LCDs, NCDs, and payer rules

ARKA's demo table mirrors the shape of real policy — supported ICD-10 lists per CPT, contrast qualifiers, and repeat windows — using synthetic identifiers only.

Medicare LCD/NCD — Local and national coverage determinations list covered indications for high-volume imaging CPTs.
Commercial payer policies — Often parallel LCD structure with plan-specific edits and prior-auth triggers.
ARKA demo fixtures — SYNTH-LCD-* rows in lib/coding/payer-policy.fixture.ts; no real payer text and no PHI.

Worked examples

Supported vs unsupported — synthetic cards

Same evaluator used when ARKA_MED_NECESSITY=1 on the CDS Hooks appropriateness service.

Aligned pair

SupportedCPT 73721

MRI knee w/o contrast

Indication ICD-10: M25.561

Indication aligns with CPT 73721 (MRI knee w/o contrast) per synthetic policy SYNTH-LCD-KNEE-MRI-WO-001. ARKA flags alignment only; clinician/coder confirms final coding.

SYNTH-LCD-KNEE-MRI-WO-001 (Synthetic demo policy table only — not a payer LCD/NCD; for illustration.)

Misaligned indication

UnsupportedCPT 72148

MRI lumbar spine w/o contrast

Indication ICD-10: Z00.00

Indication Z00.00 is not listed among supported diagnoses for CPT 72148 in the synthetic demo policy table.

Smallest fix: If clinically appropriate, add supporting indication ICD-10 M54.5 to the order reason.

SYNTH-LCD-LUMBAR-MRI-WO-001 (Synthetic demo policy table only — not a payer LCD/NCD; for illustration.)

This recommendation is intended to support, not replace, clinical judgment. It is generated by ARKA, software designed to meet the four criteria for Non-Device Clinical Decision Support under FD&C Act §520(o)(1)(E) and FDA's final guidance on Clinical Decision Support Software (January 2026). The clinician is responsible for the final decision.

At order entry

How ARKA checks alignment

Behind the ARKA_MED_NECESSITY feature flag on order-select CDS Hooks.

Read CPT and ICD-10 from the draft FHIR ServiceRequest (no PHI persisted).
Match against organization or demo policy rows via evaluateMedicalNecessity().
Append a card extension with status chip, reason, optional smallest documentation fix, and policy citation — never a final billing code.
Clinician reviews, documents, and signs; coder assigns final codes.

FDA Non-Device CDS rationale CDS Hooks live demo

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