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ICD-10-CM 2027 diagnosis code

G09Sequelae of inflammatory diseases of central nervous system

✓ Billable / specific

G09 is a valid, billable ICD-10-CM code for sequelae of inflammatory diseases of central nervous system. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.

Looking up by condition? See ICD-10 code for Encephalitis or encephalomyelitis sequelae.

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 G09

G09 is the ICD-10-CM diagnosis code for sequelae of inflammatory diseases of central nervous system. It belongs to 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.

Code first: condition resulting from (sequela) of inflammatory diseases of central nervous system.

It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.

In MS-DRG v44.0, it is part of the grouping logic for DRG 091 (Other Disorders of Nervous System with MCC, relative weight 1.7046), DRG 092 (Other Disorders of Nervous System with CC, relative weight 1.0239) and DRG 093 (Other Disorders of Nervous System without CC/MCC, relative weight 0.7783), in MDC 01 (Diseases and Disorders of the Nervous System), 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 326 (late effects of intracranial abscess or pyogenic infection).

Coding notes

Note
  • Category G09 is to be used to indicate conditions whose primary classification is to G00-G08 as the cause of sequelae, themselves classifiable elsewhere. The 'sequelae' include conditions specified as residuals.
Code firstSequence the underlying condition first
  • condition resulting from (sequela) of inflammatory diseases of central nervous system

Notes that apply from higher levels

Instructions written at a parent level also apply to G09.

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

Alphabetic index entries

14 entries

Terms in the official ICD-10-CM index that lead to G09.

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.

ICD-9-CM equivalent

Converter →
  • 326Late effects of intracranial abscess or pyogenic infectionapproximate

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 G09

Is G09 billable?

Yes. G09 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).

Can G09 be used as a principal diagnosis?

Yes. The Medicare Code Editor doesn't restrict G09 as a principal diagnosis.

Is G09 a CC or MCC?

No. G09 is neither a CC nor an MCC under MS-DRG v44.0.

What DRG does G09 group to?

G09 is used in the MS-DRG v44.0 logic for MS-DRG 091 (Other Disorders of Nervous System with MCC), MS-DRG 092 (Other Disorders of Nervous System with CC) and MS-DRG 093 (Other Disorders of Nervous System without CC/MCC). 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 G09?

The CMS General Equivalence Mappings map G09 to ICD-9-CM 326.