Question 1

What is ICD-10 code I81?

Accepted Answer

I81 is the ICD-10-CM diagnosis code for portal vein thrombosis. Blood clot formation in the portal vein, which carries blood from the digestive organs to the liver, potentially causing serious complications. I81 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).

I81 is a billable ICD-10-CM code but does not map to a payment HCC under the CMS-HCC V28, V24, ESRD, or RxHCC risk adjustment models. It can be reported on Medicare Advantage encounter data submissions but it does not contribute to a beneficiary's RAF score and therefore does not affect risk-adjusted payments to the plan.

Document whether thrombosis is acute or chronic; this may affect treatment and prognosis documentation.

Question 2

Is I81 an HCC code?

Accepted Answer

No. I81 is a billable ICD-10-CM code but does not map to any payment HCC category under the CMS-HCC V28, V24, ESRD, or RxHCC risk adjustment models. It can still be reported on Medicare Advantage encounter data submissions, but it does not contribute to the beneficiary's Risk Adjustment Factor (RAF) score and therefore does not affect the risk-adjusted capitation payment to the plan. V28 reached 100% phase-in for payment year 2026.

Question 3

Is I81 billable?

Accepted Answer

Yes. I81 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. I81 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.

Question 4

What is the V28 vs V24 difference for I81?

Accepted Answer

I81 does not map to a payment HCC under either the CMS-HCC V28 risk adjustment model or the older V24 model. V28 reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition. Because neither model rewards I81 with a risk adjustment factor, it contributes zero to a Medicare Advantage beneficiary's RAF score in either version. Coders should check whether provider documentation supports a more specific child code that does map to a payment HCC.

Question 5

What should coders know when reporting I81?

Accepted Answer

Document whether thrombosis is acute or chronic; this may affect treatment and prognosis documentation Investigate underlying causes such as cirrhosis, malignancy, or hypercoagulable states for complete clinical picture

I81

Is I81 an HCC code?

What This Code Means

Coding Tips

Excludes 2 — Not included here, may code separately

Code Hierarchy

Open I81 in the Interactive Encoder