What is ICD-10 code I82.C21?

I82.C21 is the ICD-10-CM diagnosis code for Chronic embolism and thrombosis of right internal jugular vein. It belongs to the ICD-10-CM chapter for diseases of the circulatory system (i00-i99). I82.C21 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. I82.C21 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.C21 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.C21 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.C21 map to under V28?

I82.C21 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.

What documentation supports I82.C21?

Verify documentation specifies 'chronic' duration and 'right' side to ensure accurate code selection, as laterality is required for this code Investigate the underlying cause (malignancy, trauma, central line placement, hypercoagulable state) as this may require additional diagnosis codes to capture the complete clinical picture Because I82.C21 maps to an HCC category, the documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) before the diagnosis is used for risk adjustment. 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 I82.C21: Chronic embolism

I82.C21 maps to CMS-HCC V28 267. A source-labeled RAF reference is available. Documentation must support MEAT. MEAT criteria · RAF Calculator · HCC coding software

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Code lookupI82.C21Effective 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.C21

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

Chronic embolism and thrombosis of right internal jugular vein

A blood clot that has formed in the right internal jugular vein (a major vein in the neck) and has persisted over time. This condition can restrict blood flow from the head and brain back to the heart.

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.CEmbolism and thrombosis of internal jugular vein

I82.C2Chronic embolism and thrombosis of internal jugular vein

I82.C21Chronic embolism and thrombosis of right internal jugular vein

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for I82.C21 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for I82.C21 in this effective period.

Related Child Codes

Official

I82.C22Chronic embolism and thrombosis of left internal jugular vein

I82.C23Chronic embolism and thrombosis of internal jugular vein, bilateral

I82.C29Chronic embolism and thrombosis of unspecified internal jugular vein

Includes

Official

ICD-10-CM does not list Includes notes for I82.C21 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for I82.C21 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for I82.C21 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for I82.C21 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for I82.C21 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Provider documentation explicitly stating chronic embolism or thrombosis of the internal jugular vein

Laterality must be documented (right 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 chronic embolism or thrombosis of the internal jugular vein

Laterality must be documented (right 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 chronic when the documentation actually supports acute presentation — always verify the acuity from the clinical note

Confusing the internal jugular 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)

Reporting a resolved thrombosis as chronic when the provider documents it is no longer present — chronic implies the clot is still there

Common Mistakes

HCC Buddy guidance

I82.C11 — Acute (not chronic) embolism and thrombosis of the right internal jugular vein; use for newly formed clots

I82.B21 — Chronic embolism and thrombosis of the right subclavian vein; different vessel near the collarbone

I80.8 — Phlebitis and thrombophlebitis of other sites; inflammatory component distinguishes this from pure 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 I82.C21 an HCC code?

Yes. I82.C21 (Chronic embolism and thrombosis of right internal jugular vein) 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.C21 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.C21
Description: Chronic embolism and thrombosis of right internal jugular vein
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.C21 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT Criteria for I82.C21

For I82.C21 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.C21 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

I82.C21 is the ICD-10-CM diagnosis code for chronic embolism and thrombosis of right internal jugular vein. A blood clot that has formed in the right internal jugular vein (a major vein in the neck) and has persisted over time. This condition can restrict blood flow from the head and brain back to the heart. I82.C21 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.C21 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.C21; 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.

Verify documentation specifies 'chronic' duration and 'right' side to ensure accurate code selection, as laterality is required for this code. Because I82.C21 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.C21 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Verify documentation specifies 'chronic' duration and 'right' side to ensure accurate code selection, as laterality is required for this code
•Investigate the underlying cause (malignancy, trauma, central line placement, hypercoagulable state) as this may require additional diagnosis codes to capture the complete clinical picture

Clinical Significance

Chronic internal jugular vein thrombosis indicates a long-standing vascular condition with persistent clot burden, reflecting ongoing risk for post-thrombotic syndrome, recurrent thromboembolism, and venous insufficiency. This diagnosis captures the sustained complexity of the patient's vascular disease and the need for long-term anticoagulation management, which is important for accurate risk adjustment.

Documentation Requirements

✓Provider documentation explicitly stating chronic embolism or thrombosis of the internal jugular vein
✓Laterality must be documented (right 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
✓Duration or timeline establishing chronicity (e.g., 'long-standing,' 'diagnosed 6 months ago')
✓Evidence of ongoing monitoring or follow-up imaging confirming persistent thrombus

Commonly Confused Codes

•I82.C11: Acute (not chronic) embolism and thrombosis of the right internal jugular vein; use for newly formed clots
•I82.B21: Chronic embolism and thrombosis of the right subclavian vein; different vessel near the collarbone
•I80.8: Phlebitis and thrombophlebitis of other sites; inflammatory component distinguishes this from pure thrombosis