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ICD-10-CM 2027 diagnosis code

R40.2ANontraumatic coma due to underlying condition

✓ Billable / specificMCC — major complication/comorbidityNot a principal dx

R40.2A is a valid, billable ICD-10-CM code for nontraumatic coma due to underlying condition. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.

Code last changed in FY2024 (effective October 1, 2023). Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About R40.2A

R40.2A is the ICD-10-CM diagnosis code for nontraumatic coma due to underlying condition. It belongs to category R40 (Somnolence, stupor and coma), block R40-R46 (symptoms and signs involving cognition, perception, emotional state and behavior) and chapter 18 (symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

Within R40.2 (coma), R40.2A is specifically for nontraumatic coma due to underlying condition. Related codes cover unspecified coma (R40.20), scale, eyes open (R40.21), scale, best verbal response (R40.22), scale, best motor response (R40.23) and Glasgow coma scale, total score (R40.24).

Don't report R40.2A together with the conditions in its Excludes1 note: coma scale, best motor response (R40.24.-), coma scale, best verbal response (R40.22.-), coma scale, eyes open (R40.21.-) and Glasgow coma scale, total score (R40.23.-).

Code first: underlying condition.

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 080 (Nontraumatic Stupor and Coma with MCC, relative weight 1.7472), DRG 081 (Nontraumatic Stupor and Coma without MCC, relative weight 0.806), DRG 791 (Prematurity with Major Problems, relative weight 4.1075) and DRG 793 (Full Term Neonate with Major Problems, relative weight 4.2195), 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 is not acceptable as the principal diagnosis for an inpatient stay; it may be reported as a secondary diagnosis.

It was added in FY2024, effective October 1, 2023.

Coding notes

Applicable toConditions and synonyms classified to this code
  • Secondary coma
Excludes1Not coded here — never report together with this code
  • coma scale, best motor response (R40.24.-)
  • coma scale, best verbal response (R40.22.-)
  • coma scale, eyes open (R40.21.-)
  • Glasgow coma scale, total score (R40.23.-)
Code firstSequence the underlying condition first
  • underlying condition

Notes that apply from higher levels

Instructions written at a parent level also apply to R40.2A.

› From R40.2 Coma
Note
  • One code from each subcategory, R40.21-R40.23, is required to complete the coma scale
Code first
  • any associated:
  • fracture of skull (S02.-)
  • intracranial injury (S06.-)
› From R40 Somnolence, stupor and coma
Excludes1
  • neonatal coma (P91.5)
  • somnolence, stupor and coma in diabetes (E08-E13)
  • somnolence, stupor and coma in hepatic failure (K72.-)
  • somnolence, stupor and coma in hypoglycemia (nondiabetic) (E15)

Broader instructions also apply from R40-R46 Symptoms and signs involving cognition, perception, emotional state and behavior and Chapter 18: Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified.

Alphabetic index entries

2 entries

Terms in the official ICD-10-CM index that lead to R40.2A.

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

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
  • FY2024 (effective 10/1/2023): Added
  • No changes since FY2024.

Common questions about R40.2A

Is R40.2A billable?

Yes. R40.2A is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).

Can R40.2A be used as a principal diagnosis?

No. It is not acceptable as the principal diagnosis for an inpatient stay; it may be reported as a secondary diagnosis.

Is R40.2A a CC or MCC?

R40.2A is an MCC (major complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.

What DRG does R40.2A group to?

R40.2A is used in the MS-DRG v44.0 logic for MS-DRG 080 (Nontraumatic Stupor and Coma with MCC), MS-DRG 081 (Nontraumatic Stupor and Coma without MCC), MS-DRG 791 (Prematurity with Major Problems) and MS-DRG 793 (Full Term Neonate with Major Problems). Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.