ICD-10-CM 2027
ICD-10 code for postinfectious leukoencephalitis
Postinfectious acute disseminated encephalitis and encephalomyelitis (postinfectious ADEM)
From the official ICD-10-CM alphabetic index entry “Leukoencephalitis › postinfectious”. Page updated September 29, 2026.
About coding postinfectious leukoencephalitis
The ICD-10-CM code for postinfectious leukoencephalitis is G04.01 (Postinfectious acute disseminated encephalitis and encephalomyelitis (postinfectious ADEM)).
Within G04.0 (acute disseminated encephalitis and encephalomyelitis (ADEM)), G04.01 is specifically for postinfectious acute disseminated encephalitis and encephalomyelitis (postinfectious ADEM). Related codes cover acute disseminated encephalitis and encephalomyelitis, unspecified (G04.00) and Postimmunization acute disseminated encephalitis, myelitis and encephalomyelitis (G04.02).
Don't report G04.01 together with the conditions in its Excludes1 note: post chickenpox encephalitis (B01.1), post measles encephalitis (B05.0) and post measles myelitis (B05.1).
As a secondary diagnosis it is an MCC (major complication or comorbidity), which can move an inpatient stay into the highest-paying "with MCC" MS-DRG of its family, unless the principal diagnosis excludes it.
Don't confuse with (Excludes1 for G04.01)
Common questions about postinfectious leukoencephalitis ICD-10 codes
What is the ICD-10 code for postinfectious leukoencephalitis?
- G04.01 — Postinfectious acute disseminated encephalitis and encephalomyelitis (postinfectious ADEM).
Is G04.01 billable?
- Yes. G04.01 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can G04.01 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict G04.01 as a principal diagnosis.
Is G04.01 a CC or MCC?
- G04.01 is an MCC (major complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.