2026 ICD-10-CM Diagnosis Code I28.9Disease of pulmonary vessels, unspecified
ICD-10-CM Codes›I00–I99›I26-I28›I28
- Billable — Valid for Submission
- Risk Adjusts — HCC 226
- Chronic Condition
I28.9 is a billable ICD-10-CM diagnosis code for disease of pulmonary vessels, unspecified. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 314 through 316. Coders also document this condition as acquired abnormality of pulmonary arterial tree. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Pulmonary heart disease.
For Medicare Advantage risk adjustment, I28.9 maps to CMS-HCC Category 226 (Heart Failure, Except End Stage and Acute) under the V28 model, adding a risk factor of about 0.360 for a community, non-dual, aged beneficiary in payment year 2026.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
I28.9 maps to a payment category in the CMS-HCC model used to risk-adjust Medicare Advantage payments. Weights are the published community factors for payment year 2026.
Source: CMS Payment Year 2026 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Acquired abnormality of pulmonary arterial tree
- Disorder of pulmonary circulation
- Peripheral pulmonary artery disease
- Pulmonary arterial tree abnormality as complication of procedure
- Pulmonary vein abnormality as complication of procedure
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Disease, diseased See Also: Syndrome;
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Vascular Diseases
Your vascular system is your body's network of blood vessels. It includes your:
The full article covers:
- What are vascular diseases?
- What causes vascular diseases?
- Who is at risk for vascular diseases?
- What are the symptoms of vascular diseases?
- How are vascular diseases diagnosed?
- How are vascular diseases treated?
- Can vascular diseases be prevented?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert I28.9 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About I28.9Overview
What is the ICD-10 code for disease of pulmonary vessels, unspecified?
The ICD-10-CM code for disease of pulmonary vessels, unspecified is I28.9 (sometimes written as I289). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
Is I28.9 (Other diseases of pulmonary vessels) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report disease of pulmonary vessels, unspecified on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does I28.9 group to?
When disease of pulmonary vessels, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 314, 315, 316, with relative weights from 0.6821 to 2.0852 depending on complications. Higher weights mean higher Medicare reimbursement.
What is the ICD-9 equivalent of I28.9?
Under the General Equivalence Mappings, disease of pulmonary vessels, unspecified converts to ICD-9-CM 417.9 (pulmon circulat dis NOS). The mapping is a direct match.
What HCC is I28.9?
I28.9 (disease of pulmonary vessels, unspecified) maps to CMS-HCC Category 226 (Heart Failure, Except End Stage and Acute), commonly written as HCC 226, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2026. It mapped to HCC 85 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. In the Part D prescription drug model it maps to RxHCC 184.
Does I28.9 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, I28.9 adds a risk adjustment factor of about 0.360 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.217 to 0.537 depending on the payment segment). A more severe related category (HCC 221, HCC 222, HCC 223, HCC 224, and HCC 225) supersedes it when both are reported. See the full factor table on the HCC 226 category page.
