DxCodebookFY2027 · Oct 1, 2026 – Sep 30, 2027

Category · FY2027

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

  • Header · not billable

I66 is not billable. The category heads 15 billable codes in FY2027, grouped under 6 subdivisions.

Index → code

  • Embolism (multiple) (paradoxical)meninges → I66.8
  • Thrombosis, thrombotic (bland) (multiple) (progressive) (silent) (vessel)cortical → I66.9
  • Thrombosis, thrombotic (bland) (multiple) (progressive) (silent) (vessel)intracranial (arterial) → I66.9

Where it sits

  1. Chapter 9 Diseases of the circulatory system (I00-I99)
  2. I60-I69 Cerebrovascular diseases (I60-I69)
  3. I66 Occlusion and stenosis of cerebral arteries, not resulting in cerebral infarction
Billable codes
15
Subdivisions
6
CC / MCC codes
0 / 0
HCC V28 codes
0
New FY2027
0
Index entries
13

Codes in I66

  1. I66.0
    Occlusion and stenosis of middle cerebral artery
    Header
  2. I66.01
    Occlusion and stenosis of right middle cerebral artery
    Billable
  3. I66.02
    Occlusion and stenosis of left middle cerebral artery
    Billable
  4. I66.03
    Occlusion and stenosis of bilateral middle cerebral arteries
    Billable
  5. I66.09
    Occlusion and stenosis of unspecified middle cerebral artery
    Billable
  6. I66.1
    Occlusion and stenosis of anterior cerebral artery
    Header
  7. I66.11
    Occlusion and stenosis of right anterior cerebral artery
    Billable
  8. I66.12
    Occlusion and stenosis of left anterior cerebral artery
    Billable
  9. I66.13
    Occlusion and stenosis of bilateral anterior cerebral arteries
    Billable
  10. I66.19
    Occlusion and stenosis of unspecified anterior cerebral artery
    Billable
  11. I66.2
    Occlusion and stenosis of posterior cerebral artery
    Header
  12. I66.21
    Occlusion and stenosis of right posterior cerebral artery
    Billable
  13. I66.22
    Occlusion and stenosis of left posterior cerebral artery
    Billable
  14. I66.23
    Occlusion and stenosis of bilateral posterior cerebral arteries
    Billable
  15. I66.29
    Occlusion and stenosis of unspecified posterior cerebral artery
    Billable
  16. I66.3
    Occlusion and stenosis of cerebellar arteries
    Billable
  17. I66.8
    Occlusion and stenosis of other cerebral arteries
    Billable
    Inclusion terms 1

    Inclusion terms

    • Occlusion and stenosis of perforating arteries
  18. I66.9
    Occlusion and stenosis of unspecified cerebral artery
    Billable

Sources of each column.

Instructions

At I66

Includes

  • embolism of cerebral artery
  • narrowing of cerebral artery
  • obstruction (complete) (partial) of cerebral artery
  • thrombosis of cerebral artery

Excludes1

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

Notes that also apply

Block I60-I69 instructions (Excludes1 1, Use additional code 8): printed on the block page.

Chapter 9 instructions (Excludes2 10): printed on the chapter 9 page.

Index entries

  • Thrombosis, thrombotic (bland) (multiple) (progressive) (silent) (vessel)cerebellar artery (anterior inferior) (posterior inferior) (superior) → I66.3
  • Embolism (multiple) (paradoxical)meninges → I66.8
  • Thrombosis, thrombotic (bland) (multiple) (progressive) (silent) (vessel)meninges (brain) (arterial) → I66.8
  • Thrombosis, thrombotic (bland) (multiple) (progressive) (silent) (vessel)cortical → I66.9
  • Thrombosis, thrombotic (bland) (multiple) (progressive) (silent) (vessel)intracranial (arterial) → I66.9
  • Embolism (multiple) (paradoxical)arterycerebellar (anterior inferior) (posterior inferior) (superior) → I66.3
  • Occlusion, occludedarterycerebellar (anterior inferior) (posterior inferior) (superior) → I66.3
  • Occlusion, occludedarterybrain or cerebral → I66.9
  • Occlusion, occludedarterycerebral → I66.9
  • Occlusion, occludedarterycerebralmiddle → I66.0-
  • Occlusion, occludedarterycerebralanterior → I66.1-
  • Occlusion, occludedarterycerebralposterior → I66.2-
  • Occlusion, occludedarterycerebralspecified NEC → I66.8

NCHS Alphabetic Index. Index first, then the Tabular List.

Hierarchy