Is I66.3 a billable ICD-10-CM code?

Yes. I66.3 is a billable, specific ICD-10-CM code and is valid for submission on a claim.

Where does I66.3 sit in the tabular list?

Diseases of the circulatory system (I00-I99), in the block Cerebrovascular diseases (I60-I69).

What cannot be coded together with I66.3?

I66.3 carries Excludes1 notes, which means the conditions they list can never be coded together with it on the same encounter. Some are written on the categories above I66.3 (I66) and apply to it just the same.

I66.3

I66.3 — Occlusion and stenosis of cerebellar arteries

Billable / specific codeICD-10-CM

I66.3 is a billable, specific ICD-10-CM code for occlusion and stenosis of cerebellar arteries. It is valid for submission on a claim.

Excludes1 inherited from the categories above I66.3

These are not written on I66.3, but they bind it: a note on a category applies to every code beneath it. Billing I66.3 with anything listed here is a denial.

Written on I66 — Occlusion and stenosis of cerebral arteries, not resulting in cerebral infarction

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

Risk adjustment

I66.3 does not map to an HCC and does not risk-adjust under CMS-HCC V28. That is normal — most ICD-10 codes do not. It still needs to be coded correctly; it just will not move a RAF score.

Medicare coverage

I66.3 is named in 51 Medicare coverage policies — 51 listing it as supporting medical necessity. Which of them applies to you depends on your Medicare contractor, and coverage genuinely differs by state.

A52868Billing and Coding: Transesophageal Echocardiography (TEE)
A52992Billing and Coding: Non-Invasive Cerebrovascular Arterial Studies
A52992Billing and Coding: Non-Invasive Cerebrovascular Arterial Studies
A56423Billing and Coding: Cardiology Non-emergent Outpatient Stress Testing

How I66.3 is indexed

Coders do not find codes by browsing the tabular list — they look them up in the alphabetic index, under the word the physician wrote. These are the index entries that lead here, so you can see which chart wordings map to I66.3.

Thrombosis, thrombotic›cerebellar artery(anterior inferior) (posterior inferior) (superior)
Embolism›artery›cerebellar(anterior inferior) (posterior inferior) (superior)
Occlusion, occluded›artery›cerebellar(anterior inferior) (posterior inferior) (superior)

Code history

I66.3 has not changed since FY2024 — no addition, revision or deletion across the three most recent ICD-10-CM releases.

Related codes at this level

Codes that share I66. If I66.3 is not quite right, the correct code is usually one of these.

Questions about I66.3

Is I66.3 a billable ICD-10-CM code?: Yes. I66.3 is a billable, specific ICD-10-CM code and is valid for submission on a claim.
Where does I66.3 sit in the tabular list?: Diseases of the circulatory system (I00-I99), in the block Cerebrovascular diseases (I60-I69).
What cannot be coded together with I66.3?: I66.3 carries Excludes1 notes, which means the conditions they list can never be coded together with it on the same encounter. Some are written on the categories above I66.3 (I66) and apply to it just the same.