What is ICD-10 code I82.A19?

I82.A19 is the ICD-10-CM diagnosis code for Acute embolism and thrombosis of unspecified axillary vein. A blood clot that suddenly forms in an axillary vein, but the specific arm (left, right, or both) is not documented. I82.A19 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. I82.A19 is part of the FY2026 ICD-10-CM code set published by the CMS National Center for Health Statistics and used on Medicare, Medicaid, and commercial claims in the United States.

Yes. I82.A19 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. I82.A19 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

What is the V28 vs V24 difference for I82.A19?

CMS phased in the V28 risk adjustment model over payment years 2024 (33%), 2025 (67%), and 2026 (100%), replacing V24. V28 consolidates HCC categories, removes some lower-acuity conditions, and recalibrates RAF weights across the entire model. For I82.A19, V28 maps to Deep Vein Thrombosis and Pulmonary Embolism at RAF 0.294 while V24 mapped to Vascular Disease at RAF 0.288. Both models can still appear in legacy data and in payer-specific lookback periods.

What should coders know when reporting I82.A19?

Use this code only when laterality cannot be determined from medical documentation Query the provider to obtain specific laterality information for more accurate coding Because I82.A19 maps to a payment HCC, the documentation must also satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's risk adjustment score.

2026 ICD-10-CM I82.A19: Acute embolism

ICD-10-CM Code View

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Code lookupI82.A19Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Diseases of the circulatory system (I00-I99) / Diseases of veins, lymphatic vessels and lymph nodes, not elsewhere classified (I80-I89)

I82.A19

Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidance

Acute embolism and thrombosis of unspecified axillary vein

A blood clot that suddenly forms in an axillary vein, but the specific arm (left, right, or both) is not documented.

Buddy Insight

Acute axillary vein thrombosis represents a significant vascular event that can lead to pulmonary embolism, post-thrombotic syndrome, and recurrent venous thromboembolism.

CMS-HCC V28

Mapped

HCC 267

Deep Vein Thrombosis and Pulm...

RAF 0.294

CMS-HCC V24

Mapped

HCC 108

Vascular Disease

RAF 0.288

ACA/HHS

Mapped

HCC 156

HHS-HCC 156

Varies by metal level

ESRD/PACE

Mapped

HCC 108

Vascular Disease

RAF 0.073

RXHCC

Mapped

HCC 215

Pulmonary Embolism and Other ...

RAF 0.228

Code Book Path

Official

I82.AEmbolism and thrombosis of axillary vein

I82.A1Acute embolism and thrombosis of axillary vein

I82.A19Acute embolism and thrombosis of unspecified axillary vein

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for I82.A19 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for I82.A19 in this effective period.

Related Child Codes

Official

I82.A11Acute embolism and thrombosis of right axillary vein

I82.A12Acute embolism and thrombosis of left axillary vein

I82.A13Acute embolism and thrombosis of axillary vein, bilateral

Includes

Official

ICD-10-CM does not list Includes notes for I82.A19 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for I82.A19 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for I82.A19 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for I82.A19 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for I82.A19 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Provider documentation explicitly stating acute embolism or thrombosis of the axillary vein

Laterality must be documented (unspecified side) — do not assume from context

Clinical findings supporting the diagnosis (e.g., swelling, pain, imaging results such as duplex ultrasound or CT venography)

Current treatment plan including anticoagulation therapy type, duration, and monitoring parameters

MEAT Support

HCC Buddy guidance

Provider documentation explicitly stating acute embolism or thrombosis of the axillary vein

Laterality must be documented (unspecified side) — do not assume from context

Clinical findings supporting the diagnosis (e.g., swelling, pain, imaging results such as duplex ultrasound or CT venography)

Current treatment plan including anticoagulation therapy type, duration, and monitoring parameters

Audit Caution

HCC Buddy guidance

Coding acute when the documentation actually supports chronic presentation — always verify the acuity from the clinical note

Defaulting to the unspecified laterality code without querying the provider — laterality is often available in imaging reports or procedure notes

Confusing the axillary vein with adjacent veins (e.g., subclavian) — verify the exact vessel documented

Failing to code the underlying etiology when documented (e.g., malignancy, central venous catheter, thoracic outlet syndrome)

Common Mistakes

HCC Buddy guidance

I82.A29 — Chronic (not acute) embolism and thrombosis of the unspecified axillary vein; use when the clot has been present long-term

I82.401-I82.429 — Acute/chronic embolism of deep veins of unspecified lower extremity; wrong anatomical location

I82.B19 — Acute embolism and thrombosis of the unspecified subclavian vein; different vessel, more proximal location near collarbone

Always query the provider for laterality before defaulting to the unspecified code; right or left-sided codes are preferred

Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →

Is I82.A19 an HCC code?

Yes. I82.A19 (Acute embolism and thrombosis of unspecified axillary vein) maps to Deep Vein Thrombosis and Pulmonary Embolism under the CMS-HCC V28 risk adjustment model (and Vascular Disease under V24), with a community non-dual aged RAF of 0.294. It is billable for payment year 2026.

Coder answer: I82.A19 is billable and maps to V28 HCC 267, Deep Vein Thrombosis and Pulmonary Embolism. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.

Code: I82.A19
Description: Acute embolism and thrombosis of unspecified axillary vein
HCC (V28): HCC 267 — Deep Vein Thrombosis and Pulmonary Embolism
RAF: 0.294
Billable: Yes
Payment year: 2026

HCC Category Mapping

V28HCC 267, Deep Vein Thrombosis and Pulmonary Embolism

0.294

V24HCC 108, Vascular Disease

0.288

ESRDHCC 108, Vascular Disease

0.073

RxHCCHCC 215, Pulmonary Embolism and Other Vascular Disease

0.228

Each model's RAF is its CMS base weight for that model's standard population, so weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.

Work I82.A19 in the Code Book — tabular path, V28 RAF, and MEAT checklist →

MEAT Criteria for I82.A19

For I82.A19 to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically, it has to be re-documented and supported each calendar year.

MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
EEvaluate: test results, medication response, or physical findings reviewed by the provider
AAssess: explicit mention in the assessment or plan with acknowledgment of status
TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis

Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed I82.A19 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

I82.A19 is the ICD-10-CM diagnosis code for acute embolism and thrombosis of unspecified axillary vein. A blood clot that suddenly forms in an axillary vein, but the specific arm (left, right, or both) is not documented. I82.A19 sits in the ICD-10-CM chapter for diseases of the circulatory system (i00-i99), within the section covering diseases of veins, lymphatic vessels and lymph nodes, not elsewhere classified (i80-i89).

Under the CMS-HCC V28 risk adjustment model, I82.A19 maps to Deep Vein Thrombosis and Pulmonary Embolism (HCC 267) with a community, non-dual, aged base RAF weight of 0.294. Under the older CMS-HCC V24 model, I82.A19 maps to Vascular Disease (HCC 108) with a community, non-dual, aged base RAF weight of 0.288. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.

Use this code only when laterality cannot be determined from medical documentation. Because I82.A19 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.

HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for I82.A19 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Use this code only when laterality cannot be determined from medical documentation
•Query the provider to obtain specific laterality information for more accurate coding

Clinical Significance

Acute axillary vein thrombosis represents a significant vascular event that can lead to pulmonary embolism, post-thrombotic syndrome, and recurrent venous thromboembolism. This diagnosis is critical for risk adjustment as it reflects active vascular disease requiring anticoagulation therapy, monitoring, and potentially invasive interventions. Accurate capture ensures appropriate resource allocation for ongoing management and complication prevention.

Documentation Requirements

✓Provider documentation explicitly stating acute embolism or thrombosis of the axillary vein
✓Laterality must be documented (unspecified side) — do not assume from context
✓Clinical findings supporting the diagnosis (e.g., swelling, pain, imaging results such as duplex ultrasound or CT venography)
✓Current treatment plan including anticoagulation therapy type, duration, and monitoring parameters
✓Date of onset or timeframe establishing the acute nature of the condition
✓Any precipitating factors (central line placement, surgery, malignancy, hypercoagulable state)

Commonly Confused Codes

•I82.A29: Chronic (not acute) embolism and thrombosis of the unspecified axillary vein; use when the clot has been present long-term
•I82.401-I82.429: Acute/chronic embolism of deep veins of unspecified lower extremity; wrong anatomical location
•I82.B19: Acute embolism and thrombosis of the unspecified subclavian vein; different vessel, more proximal location near collarbone
•Always query the provider for laterality before defaulting to the unspecified code; right or left-sided codes are preferred