I66.01 — Occlusion and stenosis of right middle cerebral artery
Is I66.01 billable?
Yes — I66.01 is billable for FY2027. I66.01 is a valid, billable ICD-10-CM code at the highest level of specificity in its branch. I66.01 may be submitted for encounters from October 1, 2026 through September 30, 2027.
I66.01 at a glance
| Code | I66.01 |
|---|---|
| Description | Occlusion and stenosis of right middle cerebral artery |
| Billable | Yes |
| Code set | ICD-10-CM FY2027 |
| Valid for encounters | October 1, 2026 – September 30, 2027 |
Which MS-DRGs does I66.01 group to?
I66.01 sits in MDC 01 and helps define the logic of 3 MS-DRGs (version 44, FY2027). Which one a stay actually groups to also depends on procedures and secondary diagnoses.
- 061Ischemic Stroke, Precerebral Occlusion or Transient Ischemia with Thrombolytic Agent with MCCmedical
- 062Ischemic Stroke, Precerebral Occlusion or Transient Ischemia with Thrombolytic Agent with CCmedical
- 063Ischemic Stroke, Precerebral Occlusion or Transient Ischemia with Thrombolytic Agent without CC/MCCmedical
How is I66.01 listed in the Alphabetic Index?
The Alphabetic Index lists these routes under I66.0, the nearest indexed parent of I66.01. Use them to find the family, then select the specific code.
- Occlusion, occluded › artery › cerebral › middle
Excludes1 — never code together — inherited from I60-I69
The conditions below can never be reported together with I66.01 on the same claim. An Excludes1 note means the two conditions cannot occur in the same patient, so reporting both is a coding error.
- traumatic intracranial hemorrhage (S06.-)
Excludes1 — never code together — inherited from I66
The conditions below can never be reported together with I66.01 on the same claim. An Excludes1 note means the two conditions cannot occur in the same patient, so reporting both is a coding error.
- Occlusion and stenosis of cerebral artery causing cerebral infarction (I63.3-I63.5)
Use additional code — inherited from I60-I69
Report an additional code alongside I66.01 to fully describe the condition. I66.01 is sequenced first.
Excludes2 — not included here — inherited from Chapter 9
The conditions below are not part of I66.01, but a patient may have both at the same time. When documentation supports it, I66.01 and the excluded code may both be reported.
- certain conditions originating in the perinatal period (P04-P96)
- certain infectious and parasitic diseases (A00-B99)
- complications of pregnancy, childbirth and the puerperium (O00-O9A)
- congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
- endocrine, nutritional and metabolic diseases (E00-E88)
- injury, poisoning and certain other consequences of external causes (S00-T88)
- neoplasms (C00-D49)
- symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
- systemic connective tissue disorders (M30-M36)
- transient cerebral ischemic attacks and related syndromes (G45.-)
How long has I66.01 existed?
I66.01 has been in ICD-10-CM since at least FY2016, the earliest fiscal year on record here.
Derived from the official order files for FY2016–FY2026. FY2017 and FY2020 publish no order file, so those years are not covered.