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I77.812 ICD-10-CM Code: Thoracoabdominal aortic ectasia

I77.812 is not a CMS-HCC payment code. MEAT criteria · RAF calculator · HCC Buddy coding tools

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FY 2026 Apr update / Diseases of the circulatory system (I00-I99) / Diseases of arteries, arterioles and capillaries (I70-I79)

I77.812

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

Thoracoabdominal aortic ectasia

An abnormal widening of the aorta that extends from the chest through the abdomen, affecting both thoracic and abdominal portions.

Buddy the Bee presenting code insight

Buddy Insight

Thoracoabdominal aortic ectasia involves mild dilation of both the thoracic and abdominal segments of the aorta, reflecting more widespread vascular disease than isolated segment involvement.

CMS-HCC V28

N/A

—

Not mapped

CMS-HCC V24

HCC 108

RAF 0.288

ACA/HHS

N/A

—

Not mapped

ESRD/PACE

HCC 108

RAF 0.073

RXHCC

N/A

—

Not mapped

Code Book Path

Official
I77.8Other specified disorders of arteries and arterioles
I77.81Aortic ectasia
I77.812Thoracoabdominal aortic ectasia

Inclusion Terms

Official
  • Ectasis aorta

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for I77.812 in this effective period.

Related Child Codes

Official
I77.810Thoracic aortic ectasia
I77.811Abdominal aortic ectasia
I77.819Aortic ectasia, unspecified site

Includes

Official

ICD-10-CM does not list Includes notes for I77.812 in this effective period.

Excludes 1

Official
  • aortic aneurysm and dissection (I71.-)

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for I77.812 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for I77.812 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for I77.812 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance
Imaging confirmation showing dilation of both thoracic and abdominal aortic segments
Measurements of both thoracic and abdominal aortic diameters
Documentation that dilation is sub-aneurysmal in both segments
Comprehensive surveillance plan with appropriate imaging modality and intervals

MEAT Support

HCC Buddy guidance
Imaging confirmation showing dilation of both thoracic and abdominal aortic segments
Measurements of both thoracic and abdominal aortic diameters
Documentation that dilation is sub-aneurysmal in both segments
Comprehensive surveillance plan with appropriate imaging modality and intervals

Audit Caution

HCC Buddy guidance
Using separate thoracic and abdominal ectasia codes instead of the combined thoracoabdominal code
Failing to document that both segments are involved when imaging shows diffuse dilation
Not upgrading to aneurysm code when either segment progresses beyond the aneurysm threshold
Confusing ectasia with true aneurysm based on size criteria

Common Mistakes

HCC Buddy guidance
I77.810 — Thoracic aortic ectasia: use when only thoracic segment is involved
I77.811 — Abdominal aortic ectasia: use when only abdominal segment is involved
I71.6 — Thoracoabdominal aortic aneurysm without rupture: use when dilation meets aneurysm criteria
I77.819 — Aortic ectasia, unspecified site: less specific option

Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →

Is I77.812 an HCC code?

Yes. I77.812 maps to Vascular Disease under the V24 model but is not retained in V28.

Code
I77.812
Description
Thoracoabdominal aortic ectasia
HCC (V28)
No CMS-HCC V28 mapping
RAF
—
Billable
Yes
Payment year
2026

HCC Category Mapping

V24HCC 108, Vascular Disease
0.288
ESRDHCC 108, Vascular Disease
0.073

Each model's RAF is its CMS base weight for that model's standard population, so weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. 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.

Work I77.812 in the Code Book — tabular path, V28 RAF, and MEAT checklist →

MEAT Criteria for I77.812

For I77.812 to 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 I77.812 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

I77.812 is the ICD-10-CM diagnosis code for thoracoabdominal aortic ectasia. An abnormal widening of the aorta that extends from the chest through the abdomen, affecting both thoracic and abdominal portions. I77.812 sits in the ICD-10-CM chapter for diseases of the circulatory system (i00-i99), within the section covering diseases of arteries, arterioles and capillaries (i70-i79).

Under the older CMS-HCC V24 model, I77.812 maps to Vascular Disease (HCC 108) with a community, non-dual, aged base RAF weight of 0.288. 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.

Ensure documentation specifies involvement of both thoracic and abdominal segments. Because I77.812 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 I77.812 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

  • •Ensure documentation specifies involvement of both thoracic and abdominal segments
  • •Monitor for progression and associated complications such as aortic regurgitation

Clinical Significance

Thoracoabdominal aortic ectasia involves mild dilation of both the thoracic and abdominal segments of the aorta, reflecting more widespread vascular disease than isolated segment involvement. This condition requires comprehensive surveillance and carries increased risk of progression to thoracoabdominal aneurysm. The extent of involvement reflects greater patient complexity for risk adjustment purposes.

Documentation Requirements

  • ✓Imaging confirmation showing dilation of both thoracic and abdominal aortic segments
  • ✓Measurements of both thoracic and abdominal aortic diameters
  • ✓Documentation that dilation is sub-aneurysmal in both segments
  • ✓Comprehensive surveillance plan with appropriate imaging modality and intervals
  • ✓Assessment of underlying connective tissue disorders or vasculitis
  • ✓Blood pressure management and cardiovascular risk reduction plan

Commonly Confused Codes

  • •I77.810: Thoracic aortic ectasia: use when only thoracic segment is involved
  • •I77.811: Abdominal aortic ectasia: use when only abdominal segment is involved
  • •I71.6: Thoracoabdominal aortic aneurysm without rupture: use when dilation meets aneurysm criteria
  • •I77.819: Aortic ectasia, unspecified site: less specific option

Child Codes

I77.810Thoracic aortic ectasia
I77.811Abdominal aortic ectasia
I77.812Thoracoabdominal aortic ectasia
I77.819Aortic ectasia, unspecified site

Code Hierarchy

└I77Other disorders of arteries and arterioles└I77.8Other specified disorders of arteries and arterioles└I77.81Aortic ectasia└I77.812Thoracoabdominal aortic ectasia
└I77.812Thoracoabdominal aortic ectasia

Because I77.812 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.

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