I77.6 vs M31.4
I77.6 (Arteritis, unspecified) compared with M31.4 (Aortic arch syndrome [Takayasu]), from the official CMS tabular data. Do not report these codes together: the official tabular list marks them Excludes1.
Can these codes be reported together?
No — do not report together. I77.6 carries an Excludes1 note covering M31.4: “aortic arch (M31.4)”
Sole exception: when the two conditions are documented as unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).
Side by side
| I77.6Arteritis, unspecified | M31.4Aortic arch syndrome [Takayasu] | |
|---|---|---|
| Billing status | Billable | Billable |
| Classification | I00-I99 — Diseases of the Circulatory System (I00-I99) | M00-M99 — Diseases of the Musculoskeletal System and Connective Tissue (M00-M99) |
| Definition | Arteritis, unspecified is a billable ICD-10-CM diagnosis code (I77.6). | Aortic arch syndrome [Takayasu] is a billable ICD-10-CM diagnosis code (M31.4). |
| Includes | Aortitis NOS Endarteritis NOS | autoimmune disease NOS collagen (vascular) disease NOS systemic autoimmune disease systemic collagen (vascular) disease |
Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources