2026 ICD-10-CM Diagnosis Code I99.9Unspecified disorder of circulatory system

ICD-10-CM Codes›I00–I99›I95-I99›I99

ICD-10-CM I99.9
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

I99.9 is a billable ICD-10-CM diagnosis code for unspecified disorder of circulatory system. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 302 through 303. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified and unspecified circulatory disease.

Code Identity

ICD-10-CM Code
I99.9
Billable Status
Yes — Valid for Submission
Code Describes
Unspecified disorder of circulatory system
Short Description
Unspecified disorder of circulatory system
Same as the full description in the CMS dataset.
Parent Code
I99
Other and unspecified disorders of circulatory system

Code Classification

ChapterI00–I99Diseases of the circulatory system
SectionI95-I99Other and unspecified disorders of the circulatory system
CategoryI99Other and unspecified disorders of circulatory system
This CodeI99.9Unspecified disorder of circulatory system

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Acute disease of cardiovascular system
  • Bilateral open angle glaucoma due to vascular disorder
  • Cardiovascular abnormality due to anomalous origin of arterial duct
  • Cardiovascular abnormality due to anomalous origin of coronary artery from pulmonary artery
  • Cardiovascular abnormality due to anomalous origin of coronary artery orifice
  • Cardiovascular abnormality due to bilateral arterial ducts
  • Cardiovascular abnormality due to infective myocarditis
  • Cardiovascular abnormality due to patent arterial duct
  • Cardiovascular sequelae of disorders
  • Cardiovascular system complication of procedure
  • Cardiovascular system problem
  • Cauda equina syndrome due to vascular disorder
  • Chronic visceral pain due to disorder
  • Chronic visceral pain due to vascular disorder
  • Corvisart's facies
  • Disease affecting entire cardiovascular system
  • Disease of circulatory system complicating pregnancy childbirth and puerperium
  • Disorder of blood vessels of thorax
  • Erythrocytosis due to cardiovascular disease
  • Erythrocytosis due to tissue hypoxemia
  • Fetal disorder due to chronic maternal cardiovascular disease
  • Hereditary angiopathy with nephropathy, aneurysms, and muscle cramps syndrome
  • Hypopituitarism due to vascular disorder
  • Impaired circulatory system function
  • Inflammatory disorder of the cardiovascular system
  • Neovascular angle closure glaucoma
  • Open angle glaucoma due to vascular disorder
  • Open angle glaucoma of left eye due to vascular disorder
  • Open angle glaucoma of right eye due to vascular disorder
  • Restrictive ophthalmopathy
  • Sequelae of cardiovascular disorders
  • Silent white matter disease due to vascular disease
  • Vascular disease of abdomen
  • Vascular disorder
  • Vascular disorder of pelvis
  • Vascular extraocular myopathy
  • White matter disorder due to vascular abnormality

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Angiopathia, angiopathy
    • Change(s) (in) (of)
      • circulatory
    • Change(s) (in) (of)
      • vascular
    • Circulation
      • defective (lower extremity)
    • Complication(s) (from) (of)
      • vascular
    • Damage
      • vascular
    • Defect, defective
      • circulation
    • Defect, defective
      • vascular (local)
    • Deficiency, deficient
      • vascular
    • Disease, diseased
      • blood
        • vessel
    • Disease, diseased
      • vascular
    • Disturbance(s)
      • circulatory
    • Disturbance(s)
      • vascular
    • Lesion(s) (nontraumatic)
      • vascular

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR CIR032
Other specified and unspecified circulatory disease
Default principal diagnosis: inpatient Yes · outpatient Yes

Convert I99.9 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
459.9 Circulatory disease NOS
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About I99.9Overview

Is I99.9 (Other and unspecified disorders of circulatory system) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report unspecified disorder of circulatory system on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does I99.9 group to?

When unspecified disorder of circulatory system is the principal diagnosis on an inpatient stay, it groups to MS-DRG 302, 303, with relative weights from 0.6732 to 1.1966 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of I99.9?

Under the General Equivalence Mappings, unspecified disorder of circulatory system converts to ICD-9-CM 459.9 (circulatory disease NOS). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.