R40.20 Unspecified coma

Billable ICD-10-CM code, FY2026. Acts as a Major Complication or Comorbidity (MCC) as a secondary diagnosis.

Applicable to

• Coma NOS
• Unconsciousness NOS

Applies from R40 Somnolence, stupor and coma

Excludes1 (never code together)

• 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)

Applies from R40.2 Coma

Code first

• any associated:
• fracture of skull (S02.-)
• intracranial injury (S06.-)

Notes

• One code from each subcategory, R40.21-R40.23, is required to complete the coma scale

Risk adjustment (HCC)

• CMS-HCC V28: HCC 202 — Coma, Brain Compression/Anoxic Damage
• CMS-HCC V22: HCC 80 — Coma, Brain Compression/Anoxic Damage
• ESRD V24: HCC 80

MS-DRG index

Defines the logic of DRG(s) 080-081 in MDC 01.

Approximate ICD-9-CM (GEMs)

• 780.01 Coma (approximate)

Code annotations containing back-references to R40.20

Back-references to R40.2

• Type 1 Excludes: R40.0 Somnolence ("coma (R40.2-)")
• Type 1 Excludes: R40.1 Stupor ("coma (R40.2-)")
• Type 1 Excludes: R55 Syncope and collapse ("unconsciousness NOS (R40.2-)")

Back-references to R40

• Type 1 Excludes: R41.82 Altered mental status, unspecified ("altered level of consciousness (R40.-)")
• Use Additional: T67.0 Heatstroke and sunstroke ("coma and stupor (R40.-)")

Diagnosis Index entries for R40.20

• Coma

Nearby codes

• R40 Somnolence, stupor and coma
• R40.0 Somnolence
• R40.1 Stupor
• R40.2 Coma
• R40.20 Unspecified coma (this code)
• R40.21 Coma scale, eyes open
• R40.211 Coma scale, eyes open, never
• R40.2110 Coma scale, eyes open, never, unspecified time
• R40.2111 Coma scale, eyes open, never, in the field [EMT or ambulance]
• R40.2112 Coma scale, eyes open, never, at arrival to emergency department