R40.2321 Coma scale, best motor response, extension, in the field [EMT or ambulance]

Billable ICD-10-CM code, FY2026.

Built from R40.232 with 7th character 1 (in the field [EMT or ambulance]).

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

Applies from R40.23 Coma scale, best motor response

7th character note

• The following appropriate 7th character is to be added to subcategory R40.23-:

7th character required

• 0 — unspecified time
• 1 — in the field [EMT or ambulance]
• 2 — at arrival to emergency department
• 3 — at hospital admission
• 4 — 24 hours or more after hospital admission

Applies from R40.232 Coma scale, best motor response, extension

Applicable to

• Abnormal extensor posturing to pain or noxious stimuli (< 2 years of age)
• Coma scale motor score of 2
• Extensor posturing to pain or noxious stimuli (2-5 years of age)

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

Medicare Code Edits (MCE v43.1 (April 2026))

• Unacceptable principal diagnosis: These codes describe a circumstance which influences care but is not a current illness or injury, or capture only an underlying condition, and are unacceptable as principal diagnosis.

Code annotations containing back-references to R40.2321

Back-references to R40.23

• Type 1 Excludes: R40.2A Nontraumatic coma due to underlying condition ("Glasgow coma scale, total score (R40.23.-)")

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 R40.2321

• Coma › with › motor response (none) › abnormal extensor posturing to pain or noxious stimuli (< 2 years of age)
• Coma › with › motor response (none) › extension
• Coma › with › motor response (none) › extensor posturing to pain or noxious stimuli (2-5 years of age)
• Coma › with › motor response (none) › score of › 2

Nearby codes

• R40.2312 Coma scale, best motor response, none, at arrival to emergency department
• R40.2313 Coma scale, best motor response, none, at hospital admission
• R40.2314 Coma scale, best motor response, none, 24 hours or more after hospital admission
• R40.232 Coma scale, best motor response, extension
• R40.2320 Coma scale, best motor response, extension, unspecified time
• R40.2321 Coma scale, best motor response, extension, in the field [EMT or ambulance] (this code)
• R40.2322 Coma scale, best motor response, extension, at arrival to emergency department
• R40.2323 Coma scale, best motor response, extension, at hospital admission
• R40.2324 Coma scale, best motor response, extension, 24 hours or more after hospital admission
• R40.233 Coma scale, best motor response, abnormal flexion
• R40.2330 Coma scale, best motor response, abnormal flexion, unspecified time