What is ICD-10 code I82.5Y1?

I82.5Y1 is the ICD-10-CM diagnosis code for Chronic embolism and thrombosis of unspecified deep veins of right proximal lower extremity. A chronic blood clot in an unspecified deep vein located in the upper portion (proximal area) of the right lower extremity. I82.5Y1 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. I82.5Y1 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. I82.5Y1 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. I82.5Y1 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 I82.5Y1 map to under V28?

I82.5Y1 maps to CMS-HCC V28 HCC 267 (Deep Vein Thrombosis and Pulmonary Embolism). The category numbers, labels, and conditions come from the CMS-HCC V28 model file for payment year 2026.

2026 ICD-10-CM I82.5Y1: Chronic embolism

I82.5Y1 maps to CMS-HCC V28 267. A source-labeled RAF reference is available. Documentation must support MEAT. MEAT criteria · RAF Calculator · free HCC coding tools

ICD-10-CM Code View

HCC Buddy Code Card

Digital ICD-10 code-book layout with official code detail, always-visible risk models, Code Trumping, and Buddy coding guidance.

Code lookupI82.5Y1Effective 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)

I82.5Y1

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

Chronic embolism and thrombosis of unspecified deep veins of right proximal lower extremity

A chronic blood clot in an unspecified deep vein located in the upper portion (proximal area) of the right lower extremity.

Buddy Insight

CMS-HCC V28

Mapped

HCC 267

Deep Vein Thrombosis and Pulm...

Code-level coefficient reference

CMS-HCC V24

Historical

Not used for standard CY2026 Medicare Advantage payment. Select a historical period to review V24.

Not used for CY2026 payment

ACA/HHS

Mapped

HCC 156

HHS-HCC 156 adult, RAF varies...

Code-level coefficient reference

ESRD/PACE

Mapped

HCC 108

Vascular Disease

Code-level coefficient reference

RXHCC

Mapped

HCC 215

Venous Thromboembolism

Code-level coefficient reference

Code Book Path

Official

I82.5Chronic embolism and thrombosis of deep veins of lower extremity

I82.5YChronic embolism and thrombosis of unspecified deep veins of proximal lower extremity

I82.5Y1Chronic embolism and thrombosis of unspecified deep veins of right proximal lower extremity

Inclusion Terms

Official

Chronic embolism and thrombosis of deep veins of thigh NOS
Chronic embolism and thrombosis of deep veins of upper leg NOS

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for I82.5Y1 in this effective period.

Related Child Codes

Official

I82.5Y2Chronic embolism and thrombosis of unspecified deep veins of left proximal lower extremity

I82.5Y3Chronic embolism and thrombosis of unspecified deep veins of proximal lower extremity, bilateral

I82.5Y9Chronic embolism and thrombosis of unspecified deep veins of unspecified proximal lower extremity

Includes

Official

ICD-10-CM does not list Includes notes for I82.5Y1 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for I82.5Y1 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for I82.5Y1 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for I82.5Y1 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for I82.5Y1 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Provider documentation explicitly stating 'chronic' deep vein thrombosis (not assumed from duration of treatment)

Clinical evidence supporting the diagnosis such as duplex ultrasound, venography, or other imaging results

Query provider for specific vein location when possible

Documentation confirming right-sided laterality

MEAT Support

HCC Buddy guidance

Provider documentation explicitly stating 'chronic' deep vein thrombosis (not assumed from duration of treatment)

Clinical evidence supporting the diagnosis such as duplex ultrasound, venography, or other imaging results

Query provider for specific vein location when possible

Documentation confirming right-sided laterality

Audit Caution

HCC Buddy guidance

Confusing acute and chronic deep vein thrombosis — these have different code families (I82.4- for acute lower extremity, I82.5- for chronic lower extremity) and the provider must explicitly document 'chronic'

Assigning unspecified laterality when documentation actually states right side; always check operative notes, imaging, and progress notes for laterality

Using an unspecified deep vein code when the specific vein (femoral, iliac, popliteal, tibial, peroneal, or calf muscular) is documented elsewhere in the chart — always code to the highest level of specificity

Assuming deep vein thrombosis is chronic solely because the patient has been on anticoagulation for a long time; the provider must explicitly document the condition as chronic

Common Mistakes

HCC Buddy guidance

I82.5Y- includes femoral, iliac, and popliteal veins collectively; if a specific vein is documented, use I82.51-, I82.52-, or I82.53- instead

I82.5Z- — Chronic embolism of unspecified deep veins of distal lower extremity; proximal refers to above the knee, distal refers to below the knee

I82.50- — Chronic embolism of unspecified deep veins of lower extremity (neither proximal nor distal specified)

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 I82.5Y1 an HCC code?

Yes. I82.5Y1 (Chronic embolism and thrombosis of unspecified deep veins of right proximal lower extremity) maps to HCC 267, Deep Vein Thrombosis and Pulmonary Embolism under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 0.294. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes. It is billable for payment year 2026.

Coder answer: I82.5Y1 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: I82.5Y1
Description: Chronic embolism and thrombosis of unspecified deep veins of right proximal lower extremity
HCC (V28): HCC 267 — Deep Vein Thrombosis and Pulmonary Embolism
RAF reference coefficient: 0.294
Billable: Yes
Payment year: 2026

HCC Category Mapping

V28HCC 267, Deep Vein Thrombosis and Pulmonary Embolism

0.294

ESRDHCC 108, Vascular Disease

Not separately weighted

RxHCCHCC 215, Venous Thromboembolism

Not separately weighted

These are source-labeled model coefficients, not member totals. A category may still be removed by hierarchy or model cleanup rules. 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 context, hierarchy and cleanup rules, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains available for historical review.

Work I82.5Y1 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT Criteria for I82.5Y1

For I82.5Y1 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 I82.5Y1 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

I82.5Y1 is the ICD-10-CM diagnosis code for chronic embolism and thrombosis of unspecified deep veins of right proximal lower extremity. A chronic blood clot in an unspecified deep vein located in the upper portion (proximal area) of the right lower extremity. I82.5Y1 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, I82.5Y1 maps to Deep Vein Thrombosis and Pulmonary Embolism (HCC 267) with a source-labeled community, non-dual, aged reference coefficient of 0.294. No V24 mapping is shown for I82.5Y1; use the applicable model and payment year when reviewing the V28 mapping. 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. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes.

This code is used when the specific deep vein in the proximal right leg cannot be identified. Because I82.5Y1 maps to an HCC category, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) before the diagnosis is used for risk adjustment. 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, source-labeled coefficient references, and MEAT documentation criteria for I82.5Y1 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•This code is used when the specific deep vein in the proximal right leg cannot be identified
•Proximal refers to the upper leg area; distinguish from distal (lower leg) locations

Clinical Significance

Chronic deep vein thrombosis of the proximal lower extremity (unspecified) indicates a long-standing thrombus that has organized within the venous system, often leading to post-thrombotic syndrome with chronic swelling, pain, and skin changes. This condition requires ongoing anticoagulation management and monitoring for recurrent thromboembolism and venous insufficiency. Accurate capture of chronic deep vein thrombosis is essential for risk adjustment as it reflects persistent vascular disease burden.

Documentation Requirements

✓Provider documentation explicitly stating 'chronic' deep vein thrombosis (not assumed from duration of treatment)
✓Clinical evidence supporting the diagnosis such as duplex ultrasound, venography, or other imaging results
✓Query provider for specific vein location when possible
✓Documentation confirming right-sided laterality
✓Current treatment plan including anticoagulation therapy and duration
✓Assessment and monitoring notes demonstrating the condition is being actively managed
✓Documentation of chronicity such as 'chronic,' 'old,' 'long-standing,' or history of prior acute deep vein thrombosis that has transitioned to chronic status

Commonly Confused Codes

•I82.5Y- includes femoral, iliac, and popliteal veins collectively; if a specific vein is documented, use I82.51-, I82.52-, or I82.53- instead
•I82.5Z-: Chronic embolism of unspecified deep veins of distal lower extremity; proximal refers to above the knee, distal refers to below the knee
•I82.50-: Chronic embolism of unspecified deep veins of lower extremity (neither proximal nor distal specified)