What is ICD-10 code G37.3?

G37.3 is the ICD-10-CM diagnosis code for Acute transverse myelitis in demyelinating disease of central nervous system. Sudden inflammation and demyelination of the spinal cord occurring as part of a demyelinating disease of the central nervous system. G37.3 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. G37.3 is part of the FY2026 ICD-10-CM code set published by the CMS National Center for Health Statistics and used on Medicare, Medicaid, and commercial claims in the United States.

Yes. G37.3 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. G37.3 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

What is the V28 vs V24 difference for G37.3?

CMS phased in the V28 risk adjustment model over payment years 2024 (33%), 2025 (67%), and 2026 (100%), replacing V24. V28 consolidates HCC categories, removes some lower-acuity conditions, and recalibrates RAF weights across the entire model. For G37.3, V28 maps to Spinal Cord Disorders/Injuries at RAF 0.282 while V24 mapped to Spinal Cord Disorders/Injuries at RAF 0.464. Both models can still appear in legacy data and in payer-specific lookback periods.

What should coders know when reporting G37.3?

Confirm acute presentation with transverse myelitis symptoms (paralysis, sensory loss, bowel/bladder dysfunction) Document the underlying demyelinating disease (MS, NMO, etc.) if known Because G37.3 maps to a payment HCC, the documentation must also satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's risk adjustment score.

G37.3 ICD-10 Code: Acute transverse myelitis

ICD-10-CM Code View

HCC Buddy Code Card

Digital ICD-10 code-book layout with official code detail, always-visible risk models, Code Trumping, and Buddy coding guidance.

Code lookupG37.3Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Diseases of the nervous system (G00-G99) / Demyelinating diseases of the central nervous system (G35-G37)

G37.3

Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidance

Acute transverse myelitis in demyelinating disease of central nervous system

Sudden inflammation and demyelination of the spinal cord occurring as part of a demyelinating disease of the central nervous system.

Buddy Insight

Acute transverse myelitis in demyelinating disease of the central nervous system represents sudden inflammation across the width of the spinal cord as part of a demyelinating disease process.

CMS-HCC V28

Mapped

HCC 182

Spinal Cord Disorders/Injuries

RAF 0.282

CMS-HCC V24

Mapped

HCC 72

Spinal Cord Disorders/Injuries

RAF 0.464

ACA/HHS

Not risk-adjusted for this model/period.

RAF 0

ESRD/PACE

Mapped

HCC 72

Spinal Cord Disorders/Injuries

RAF 0.0

RXHCC

Mapped

HCC 155

Myelitis and Encephalomyelitis

RAF 0.0

Code Trumping

Basket needed

Compare selected patient codes to show trumped or trumps impact.

Code Book Path

Official

G37Other demyelinating diseases of central nervous system

G37.3Acute transverse myelitis in demyelinating disease of central nervous system

Inclusion Terms

Official

Acute transverse myelitis NOS
Acute transverse myelopathy

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for G37.3 in this effective period.

Related Child Codes

Official

G37.0Diffuse sclerosis of central nervous system

G37.1Central demyelination of corpus callosum

G37.2Central pontine myelinolysis

G37.4Subacute necrotizing myelitis of central nervous system

G37.5Concentric sclerosis [Balo] of central nervous system

Includes

Official

ICD-10-CM does not list Includes notes for G37.3 in this effective period.

Excludes 1

Official

acute flaccid myelitis (G04.82)
multiple sclerosis (G35-)
neuromyelitis optica [Devic] (G36.0)

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for G37.3 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for G37.3 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for G37.3 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Documentation of acute transverse myelitis confirmed by clinical presentation and imaging

MRI of the spine showing inflammatory lesion extending across the cord

Documentation linking the myelitis to an underlying demyelinating disease

Neurological examination documenting level of the lesion and deficits below it

MEAT Support

HCC Buddy guidance

Documentation of acute transverse myelitis confirmed by clinical presentation and imaging

MRI of the spine showing inflammatory lesion extending across the cord

Documentation linking the myelitis to an underlying demyelinating disease

Neurological examination documenting level of the lesion and deficits below it

Audit Caution

HCC Buddy guidance

Using unspecified myelitis codes when the demyelinating context and acute nature are documented

Not coding the underlying demyelinating disease (MS, NMO) when it has been identified

Confusing acute transverse myelitis with compressive myelopathy from spinal stenosis or disc disease

Failing to document the level of the spinal cord lesion, which affects coding of associated motor/sensory deficits

Common Mistakes

HCC Buddy guidance

G37.4 — Subacute necrotizing myelitis; slower onset with necrotizing features rather than acute inflammatory

G04.91 — Myelitis, unspecified; does not specify the demyelinating context

G36.0 — Neuromyelitis optica; may present with transverse myelitis but is a distinct disease entity

G95.0 — Syringomyelia and syringobulbia; cavity formation in spinal cord, not inflammatory

Last updated: FY2026 ICD-10-CM Apr update, Apr 1, 2026 through Sep 30, 2026. CMS-HCC V28 is 100% phased in for payment year 2026.

Is G37.3 an HCC code?

Yes. G37.3 maps to Spinal Cord Disorders/Injuries under the CMS-HCC V28 risk adjustment model (and Spinal Cord Disorders/Injuries under V24).

HCC Category Mapping

V28HCC 182, Spinal Cord Disorders/Injuries

0.282

V24HCC 72, Spinal Cord Disorders/Injuries

0.464

ESRDHCC 72, Spinal Cord Disorders/Injuries

0.000

RxHCCHCC 155, Myelitis and Encephalomyelitis

0.000

RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.

MEAT Criteria for G37.3

For G37.3to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically, it has to be re-documented and supported each calendar year.

MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
EEvaluate: test results, medication response, or physical findings reviewed by the provider
AAssess: explicit mention in the assessment or plan with acknowledgment of status
TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis

Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed G37.3 during that encounter, not just copy-forwarded from a problem list.

What This Code Means

G37.3 is the ICD-10-CM diagnosis code for acute transverse myelitis in demyelinating disease of central nervous system. Sudden inflammation and demyelination of the spinal cord occurring as part of a demyelinating disease of the central nervous system. G37.3 sits in the ICD-10-CM chapter for diseases of the nervous system (g00-g99), within the section covering demyelinating diseases of the central nervous system (g35-g37).

Under the CMS-HCC V28 risk adjustment model, G37.3 maps to Spinal Cord Disorders/Injuries (HCC 182) with a community, non-dual, aged base RAF weight of 0.282. Under the older V24 model, G37.3 mapped to the same category but with a base RAF weight of 0.464, V28 recalibrated weights across the entire model. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.

Confirm acute presentation with transverse myelitis symptoms (paralysis, sensory loss, bowel/bladder dysfunction). Because G37.3 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.

HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for G37.3 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Confirm acute presentation with transverse myelitis symptoms (paralysis, sensory loss, bowel/bladder dysfunction)
•Document the underlying demyelinating disease (MS, NMO, etc.) if known

Clinical Significance

Acute transverse myelitis in demyelinating disease of the central nervous system represents sudden inflammation across the width of the spinal cord as part of a demyelinating disease process. It causes rapid-onset paralysis, sensory loss, and bowel/bladder dysfunction below the level of the lesion. Accurate capture is critical as it reflects both the acute severity and the underlying chronic demyelinating condition.

Documentation Requirements

✓Documentation of acute transverse myelitis confirmed by clinical presentation and imaging
✓MRI of the spine showing inflammatory lesion extending across the cord
✓Documentation linking the myelitis to an underlying demyelinating disease
✓Neurological examination documenting level of the lesion and deficits below it
✓Timeline of symptom onset (hours to days) confirming acute presentation
✓Treatment documentation (high-dose corticosteroids, plasma exchange)
✓Assessment for bowel and bladder dysfunction

Excludes 1, Do NOT code together

acute flaccid myelitis (G04.82)
multiple sclerosis (G35-)
neuromyelitis optica [Devic] (G36.0)

Commonly Confused Codes

•G37.4 — Subacute necrotizing myelitis; slower onset with necrotizing features rather than acute inflammatory
•G04.91 — Myelitis, unspecified; does not specify the demyelinating context
•G36.0 — Neuromyelitis optica; may present with transverse myelitis but is a distinct disease entity
•G95.0 — Syringomyelia and syringobulbia; cavity formation in spinal cord, not inflammatory
•G35 — Multiple sclerosis; may cause transverse myelitis but the underlying MS should be coded