U.S. ICD-10-CM · FY 2027

I66 ICD-10-CM Code: Occlusion and stenosis of cerebral arteries, not resulting in cerebral infarction

A clear reference for the official code description, hierarchy, and related coding information from the FY 2027 U.S. release.

Code definition

Official description

I66

Occlusion and stenosis of cerebral arteries, not resulting in cerebral infarction

ICD-10-CM diagnosis code · United States clinical modification

Classification

Where I66 sits

  1. 1

    Chapter 9

    Diseases of the circulatory system (I00-I99)

  2. 2

    Section

    Cerebrovascular diseases (I60-I69)

  3. 3

    Category I66

    Occlusion and stenosis of cerebral arteries, not resulting in cerebral infarction

  4. 4

    Code I66

    Occlusion and stenosis of cerebral arteries, not resulting in cerebral infarction

More specific choices

Codes under I66

I66 is a non-billable category. Choose the child code that best matches the documented diagnosis.

Documentation details

Notes for this code

Inclusion terms

No inclusion terms are listed for I66.

Code first

No “code first” instruction is listed for I66.

Use additional code

No “use additional code” instruction is listed for I66.

Excludes1

Conditions that should not be reported together with this code.

  • Occlusion and stenosis of cerebral artery causing cerebral infarction (I63.3-I63.5)

Excludes2

Conditions not included here that may be reported separately when present.

No Excludes2 note is listed for I66.

Transparency

Source and release

Data release

U.S. ICD-10-CM · FY 2027

Effective date

Oct 1, 2026

This reference is generated from Vero’s ICD-10-CM description, hierarchy, and code-note dataset. The visible content and structured data share that source.

Review the CDC/NCHS ICD-10-CM source

Code-specific guidance

Frequently asked questions

What does ICD-10-CM code I66 mean?

I66 is the FY 2027 U.S. ICD-10-CM code for “Occlusion and stenosis of cerebral arteries, not resulting in cerebral infarction.”

Is I66 a billable or specific ICD-10-CM code?

No. I66 has more specific child codes in the FY 2027 reference data. Select the code that matches the documentation and confirm the active code set and payer requirements.

Where is I66 located in ICD-10-CM?

I66 is listed in Chapter 9, Diseases of the circulatory system (I00-I99), within Cerebrovascular diseases (I60-I69) (I60–I69), under category I66, Occlusion and stenosis of cerebral arteries, not resulting in cerebral infarction.

What coding notes are listed for I66?

No inclusion terms are listed for I66 in this reference record. No code-first instruction is listed. Excludes1 notes: Occlusion and stenosis of cerebral artery causing cerebral infarction (I63.3-I63.5). No Excludes2 note is listed.

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