B01.1 vs G04.01
B01.1 (Varicella encephalitis, myelitis and encephalomyelitis) compared with G04.01 (Postinfectious acute disseminated encephalitis and encephalomyelitis (postinfectious ADEM)), 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. G04.01 carries an Excludes1 note covering B01.1: “post chickenpox encephalitis (B01.1)”
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
| B01.1Varicella encephalitis, myelitis and encephalomyelitis | G04.01Postinfectious acute disseminated encephalitis and encephalomyelitis (postinfectious ADEM) | |
|---|---|---|
| Billing status | Non-billable header | Billable |
| Classification | A00-B99 — Certain Infectious and Parasitic Diseases (A00-B99) | G00-G99 — Diseases of the Nervous System (G00-G99) |
| Definition | Varicella encephalitis, myelitis and encephalomyelitis is a non-billable ICD-10-CM category code (B01.1). | Postinfectious acute disseminated encephalitis and encephalomyelitis (postinfectious ADEM) is a billable ICD-10-CM diagnosis code (G04.01). |
| Includes | Postchickenpox encephalitis, myelitis and encephalomyelitis | acute ascending myelitis meningoencephalitis meningomyelitis |
Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources