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ICD-10-CM 2027 diagnosis code

G04.2Bacterial meningoencephalitis and meningomyelitis, not elsewhere classified

✓ Billable / specificMCC — major complication/comorbidity

G04.2 is a valid, billable ICD-10-CM code for bacterial meningoencephalitis and meningomyelitis, not elsewhere classified. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.Short description: Bacterial meningoencephalitis and meningomyelitis, NEC

Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About G04.2

G04.2 is the ICD-10-CM diagnosis code for bacterial meningoencephalitis and meningomyelitis, not elsewhere classified. It belongs to category G04 (encephalitis, myelitis and encephalomyelitis), block G00-G09 (inflammatory diseases of the central nervous system) and chapter 6 (diseases of the nervous system). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

Within G04 (encephalitis, myelitis and encephalomyelitis), G04.2 is specifically for bacterial meningoencephalitis and meningomyelitis, not elsewhere classified. Related codes cover acute disseminated encephalitis and encephalomyelitis (ADEM) (G04.0), tropical spastic paraplegia (G04.1), acute necrotizing hemorrhagic encephalopathy (G04.3), other encephalitis, myelitis and encephalomyelitis (G04.8) and unspecified (G04.9).

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.

In MS-DRG v44.0, it is part of the grouping logic for DRG 023 (Craniotomy with Major Device Implant or Acute Complex CNS Principal Diagnosis with MCC or Antineoplastic Implant or Epilepsy with Neurostimulator, relative weight 5.7444), DRG 024 (Craniotomy with Major Device Implant or Acute Complex CNS Principal Diagnosis without MCC, relative weight 3.9708), DRG 094 (Bacterial and Tuberculous Infections of Nervous System with MCC, relative weight 3.4124), DRG 095 (Bacterial and Tuberculous Infections of Nervous System with CC, relative weight 2.3492), DRG 096 (Bacterial and Tuberculous Infections of Nervous System without CC/MCC, relative weight 2.3213), DRG 791 (Prematurity with Major Problems, relative weight 4.1075) and 1 more, in MDC 01 (Diseases and Disorders of the Nervous System) and MDC 15 (Newborns and Other Neonates with Conditions Originating in the Perinatal Period), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Before ICD-10, this condition was coded in ICD-9-CM as 320.9 (meningitis due to unspecified bacterium).

Notes that apply from higher levels

Instructions written at a parent level also apply to G04.2.

› From G04 Encephalitis, myelitis and encephalomyelitis
Includes
  • acute ascending myelitis
  • meningoencephalitis
  • meningomyelitis
Excludes1
Excludes2
  • acute transverse myelitis (G37.3)
  • alcoholic encephalopathy (G31.2)
  • multiple sclerosis (G35-)
  • myalgic encephalomyelitis (G93.32)
  • subacute necrotizing myelitis (G37.4)
  • toxic encephalitis (G92.8)
  • toxic encephalopathy (G92.8)

Broader instructions also apply from Chapter 6: Diseases of the nervous system.

Alphabetic index entries

5 entries

Terms in the official ICD-10-CM index that lead to G04.2.

Codes whose notes reference G04.2

MS-DRG v44.0 grouping

All DRGs →

Inpatient MS-DRGs this diagnosis can group to, as the principal or a secondary diagnosis, depending on the rest of the claim.

MDC 15 · Newborns and Other Neonates with Conditions Originating in the Perinatal Period

MDC 15 · Newborns and Other Neonates with Conditions Originating in the Perinatal Period

ICD-9-CM equivalent

Converter →
  • 320.9Meningitis due to unspecified bacteriumapproximate

From the CMS 2018 General Equivalence Mappings (GEMs), the final GEMs release.

Code history

  1. 2016
  2. 2017
  3. 2018
  4. 2019
  5. 2020
  6. 2021
  7. 2022
  8. 2023
  9. 2024
  10. 2025
  11. 2026
  12. 2027
  • FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
  • No changes since FY2016.

Common questions about G04.2

Is G04.2 billable?

Yes. G04.2 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).

Can G04.2 be used as a principal diagnosis?

Yes. The Medicare Code Editor doesn't restrict G04.2 as a principal diagnosis.

Is G04.2 a CC or MCC?

G04.2 is an MCC (major complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.

What DRG does G04.2 group to?

G04.2 is used in the MS-DRG v44.0 logic for MS-DRG 023 (Craniotomy with Major Device Implant or Acute Complex CNS Principal Diagnosis with MCC or Antineoplastic Implant or Epilepsy with Neurostimulator), MS-DRG 024 (Craniotomy with Major Device Implant or Acute Complex CNS Principal Diagnosis without MCC), MS-DRG 094 (Bacterial and Tuberculous Infections of Nervous System with MCC), MS-DRG 095 (Bacterial and Tuberculous Infections of Nervous System with CC), MS-DRG 096 (Bacterial and Tuberculous Infections of Nervous System without CC/MCC), MS-DRG 791 (Prematurity with Major Problems) and 1 more. Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.

What is the ICD-9 code for G04.2?

The CMS General Equivalence Mappings map G04.2 to ICD-9-CM 320.9.