What is ICD-10 code I80.209?

I80.209 is the ICD-10-CM diagnosis code for Phlebitis and thrombophlebitis of unspecified deep vessels of unspecified lower extremity. Inflammation and blood clot formation in an unspecified deep vein of the lower leg, but it's unclear which leg is affected. I80.209 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. I80.209 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. I80.209 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. I80.209 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.

Which HCC does I80.209 map to under V28?

I80.209 maps to CMS-HCC V28 267 (Deep Vein Thrombosis and Pulmonary Embolism). The category number and label come from the CMS-HCC V28 model file for payment year 2026.

What does I80.209 pay in RAF?

I80.209 carries a community, non-dual, aged (CNA) RAF weight of 0.294 under CMS-HCC V28 for payment year 2026. The weight comes from the CMS V28 relative-factor file, not a hand-typed table.

What is the V28 vs V24 difference for I80.209?

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 I80.209, 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 documentation supports I80.209?

This is a less specific code; query the provider to determine laterality (right, left, or bilateral) for more accurate coding Verify if the deep vein thrombosis is associated with a specific vessel (popliteal, tibial, peroneal, or iliac) to assign a more specific code Because I80.209 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. See the MEAT criteria checklist at /meat-criteria for what Monitor, Evaluate, Assess, or Treat looks like in a note. MEAT is generic documentation evidence, not a payer-specific rule.

2026 ICD-10-CM I80.209: Phlebitis

I80.209 maps to CMS-HCC V28 267 (RAF 0.294). Documentation must support MEAT. MEAT criteria · RAF calculator · HCC Buddy coding tools

ICD-10-CM Code View

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Code lookupI80.209Effective 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)

I80.209

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

Phlebitis and thrombophlebitis of unspecified deep vessels of unspecified lower extremity

Inflammation and blood clot formation in an unspecified deep vein of the lower leg, but it's unclear which leg is affected.

Buddy Insight

Phlebitis and thrombophlebitis of unspecified deep vessels of the unspecified lower extremity indicates deep vein thrombosis without specification of the exact vein involved.

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

I80.2Phlebitis and thrombophlebitis of other and unspecified deep vessels of lower extremities

I80.20Phlebitis and thrombophlebitis of unspecified deep vessels of lower extremities

I80.209Phlebitis and thrombophlebitis of unspecified deep vessels of unspecified lower extremity

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for I80.209 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for I80.209 in this effective period.

Related Child Codes

Official

I80.201Phlebitis and thrombophlebitis of unspecified deep vessels of right lower extremity

I80.202Phlebitis and thrombophlebitis of unspecified deep vessels of left lower extremity

I80.203Phlebitis and thrombophlebitis of unspecified deep vessels of lower extremities, bilateral

Includes

Official

ICD-10-CM does not list Includes notes for I80.209 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for I80.209 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for I80.209 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for I80.209 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for I80.209 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Imaging confirmation of deep vein thrombosis (duplex ultrasound or CT venography)

Laterality — query provider for specific side

Query provider for specific deep vein involvement when possible

Acuity — acute, subacute, or chronic thrombosis

MEAT Support

HCC Buddy guidance

Imaging confirmation of deep vein thrombosis (duplex ultrasound or CT venography)

Laterality — query provider for specific side

Query provider for specific deep vein involvement when possible

Acuity — acute, subacute, or chronic thrombosis

Audit Caution

HCC Buddy guidance

Using this unspecified code when the ultrasound report identifies the specific vein involved

Failing to review the imaging report which typically specifies the exact vein(s) affected

Not querying the provider for vein specification when available from imaging

Confusing deep and superficial venous thrombosis

Common Mistakes

HCC Buddy guidance

I80.10-I80.13 — Phlebitis/thrombophlebitis of femoral vein: use when femoral vein is specified

I80.22x — Phlebitis/thrombophlebitis of popliteal vein: use when popliteal vein is specified

I80.23x — Phlebitis/thrombophlebitis of tibial vein: use when tibial vein is specified

I80.0x — Superficial vessel thrombophlebitis: different clinical significance, not deep vein thrombosis

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 I80.209 an HCC code?

Yes. I80.209 (Phlebitis and thrombophlebitis of unspecified deep vessels of unspecified lower extremity) 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: I80.209 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: I80.209
Description: Phlebitis and thrombophlebitis of unspecified deep vessels of unspecified lower extremity
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 I80.209 in the Code Book — tabular path, V28 RAF, and MEAT checklist →

MEAT Criteria for I80.209

For I80.209 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 I80.209 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

I80.209 is the ICD-10-CM diagnosis code for phlebitis and thrombophlebitis of unspecified deep vessels of unspecified lower extremity. Inflammation and blood clot formation in an unspecified deep vein of the lower leg, but it's unclear which leg is affected. I80.209 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, I80.209 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, I80.209 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.

This is a less specific code; query the provider to determine laterality (right, left, or bilateral) for more accurate coding. Because I80.209 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 I80.209 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•This is a less specific code; query the provider to determine laterality (right, left, or bilateral) for more accurate coding
•Verify if the deep vein thrombosis is associated with a specific vessel (popliteal, tibial, peroneal, or iliac) to assign a more specific code

Clinical Significance

Phlebitis and thrombophlebitis of unspecified deep vessels of the unspecified lower extremity indicates deep vein thrombosis without specification of the exact vein involved. Deep vein thrombosis is a significant condition carrying risk of pulmonary embolism and post-thrombotic syndrome. While this code captures the deep vein thrombosis, providers should be queried for the specific vein (femoral, popliteal, tibial) to enable more precise coding.

Documentation Requirements

✓Imaging confirmation of deep vein thrombosis (duplex ultrasound or CT venography)
✓Laterality — query provider for specific side
✓Query provider for specific deep vein involvement when possible
✓Acuity — acute, subacute, or chronic thrombosis
✓Evaluation for pulmonary embolism
✓Anticoagulation plan with agent, dose, and planned duration
✓Risk factor assessment including malignancy screening if appropriate

Commonly Confused Codes

•I80.10-I80.13: Phlebitis/thrombophlebitis of femoral vein: use when femoral vein is specified
•I80.22x: Phlebitis/thrombophlebitis of popliteal vein: use when popliteal vein is specified
•I80.23x: Phlebitis/thrombophlebitis of tibial vein: use when tibial vein is specified
•I80.0x: Superficial vessel thrombophlebitis: different clinical significance, not deep vein thrombosis
•I82.40x: Acute embolism and thrombosis: verify correct code series