What is ICD-10 code I70.563?

I70.563 is the ICD-10-CM diagnosis code for Atherosclerosis of nonautologous biological bypass graft(s) of the extremities with gangrene, bilateral legs. Hardening of arteries in biological bypass grafts with tissue death (gangrene) affecting both legs. It belongs to the ICD-10-CM chapter for diseases of the circulatory system (i00-i99). I70.563 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. I70.563 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. I70.563 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. I70.563 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 I70.563?

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 I70.563, V28 maps to Atherosclerosis of the Extremities with Ulceration or Gangrene at RAF 0.742 while V24 mapped to Atherosclerosis of the Extremities with Ulceration or Gangrene at RAF 0.860. Both models can still appear in legacy data and in payer-specific lookback periods.

What should coders know when reporting I70.563?

This code indicates bilateral involvement; ensure documentation confirms gangrene in both legs. Bilateral gangrene is a serious condition; verify this is not a documentation error before coding. Because I70.563 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.

I70.563 ICD-10 Code: Atherosclerosis

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 lookupI70.563Effective periodFY2026 Apr Update (Apr 1-Sep 30)

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

I70.563

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

Atherosclerosis of nonautologous biological bypass graft(s) of the extremities with gangrene, bilateral legs

Hardening of arteries in biological bypass grafts with tissue death (gangrene) affecting both legs.

Buddy Insight

CMS-HCC V28

Mapped

HCC 263

Atherosclerosis of the Extrem...

RAF 0.742

CMS-HCC V24

Mapped

HCC 106

Atherosclerosis of the Extrem...

RAF 0.860

ACA/HHS

Not risk-adjusted for this model/period.

RAF 0

ESRD/PACE

Mapped

HCC 106

Atherosclerosis of the Extrem...

RAF 0.0

RXHCC

Not risk-adjusted for this model/period.

RAF 0

Code Trumping

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Compare selected patient codes to show trumped or trumps impact.

Code Book Path

Official

I70.5Atherosclerosis of nonautologous biological bypass graft(s) of the extremities

I70.56Atherosclerosis of nonautologous biological bypass graft(s) of the extremities with gangrene

I70.563Atherosclerosis of nonautologous biological bypass graft(s) of the extremities with gangrene, bilateral legs

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for I70.563 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for I70.563 in this effective period.

Related Child Codes

Official

I70.561Atherosclerosis of nonautologous biological bypass graft(s) of the extremities with gangrene, right leg

I70.562Atherosclerosis of nonautologous biological bypass graft(s) of the extremities with gangrene, left leg

I70.568Atherosclerosis of nonautologous biological bypass graft(s) of the extremities with gangrene, other extremity

I70.569Atherosclerosis of nonautologous biological bypass graft(s) of the extremities with gangrene, unspecified extremity

Includes

Official

any condition classifiable to I70.51-, I70.52-, and I70.53-, I70.54-, I70.55
chronic limb-threatening ischemia of nonautologous biological bypass graft(s) of the extremities with gangrene
critical limb ischemia of nonautologous biological bypass graft(s) of the extremities with gangrene

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for I70.563 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for I70.563 in this effective period.

Use Additional

Official

code to identify the severity of any ulcer (L97.-, L98.49-), if applicable

Code Also

Official

ICD-10-CM does not list Code Also instructions for I70.563 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Documentation of the type of bypass graft as nonautologous biological (must distinguish from autologous vein, nonautologous biological, or synthetic/nonbiological grafts)

Clinical evidence of atherosclerosis affecting the bypass graft (imaging, angiography, or clinical assessment)

Documentation of gangrene with description of extent and affected tissue

Assessment of the affected extremity including viability of surrounding tissue

MEAT Support

HCC Buddy guidance

Documentation of the type of bypass graft as nonautologous biological (must distinguish from autologous vein, nonautologous biological, or synthetic/nonbiological grafts)

Clinical evidence of atherosclerosis affecting the bypass graft (imaging, angiography, or clinical assessment)

Documentation of gangrene with description of extent and affected tissue

Assessment of the affected extremity including viability of surrounding tissue

Audit Caution

HCC Buddy guidance

Confusing nonautologous biological grafts (donor or animal tissue) with autologous vein grafts (patient's own vein) or synthetic nonbiological grafts — each has a distinct code range

Coding gangrene without confirming tissue necrosis is documented — dry gangrene versus wet gangrene should be noted but both qualify

Missing the requirement to also code the specific gangrene type (such as I96) when applicable per coding guidelines

Failing to distinguish atherosclerotic gangrene from diabetic gangrene — review the provider's attribution carefully

Common Mistakes

HCC Buddy guidance

I70.4xx — Autologous vein bypass graft codes; use when the graft is the patient's own harvested vein, not donor or animal tissue

I70.6xx — Nonbiological bypass graft codes; use when a synthetic graft material (such as Dacron or polytetrafluoroethylene) is used rather than biological tissue

I70.2xx — Native artery atherosclerosis codes; use when no bypass graft is present and disease is in the patient's own arteries

I70.52x — Atherosclerosis of same graft type with rest pain; use when there is critical ischemia pain but no tissue necrosis

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 I70.563 an HCC code?

Yes. I70.563 maps to Atherosclerosis of the Extremities with Ulceration or Gangrene under the CMS-HCC V28 risk adjustment model (and Atherosclerosis of the Extremities with Ulceration or Gangrene under V24).

HCC Category Mapping

V28HCC 263, Atherosclerosis of the Extremities with Ulceration or Gangrene

0.742

V24HCC 106, Atherosclerosis of the Extremities with Ulceration or Gangrene

0.860

ESRDHCC 106, Atherosclerosis of the Extremities with Ulceration or Gangrene

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 I70.563

For I70.563to 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 I70.563 during that encounter, not just copy-forwarded from a problem list.

What This Code Means

I70.563 is the ICD-10-CM diagnosis code for atherosclerosis of nonautologous biological bypass graft(s) of the extremities with gangrene, bilateral legs. Hardening of arteries in biological bypass grafts with tissue death (gangrene) affecting both legs. I70.563 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 CMS-HCC V28 risk adjustment model, I70.563 maps to Atherosclerosis of the Extremities with Ulceration or Gangrene (HCC 263) with a community, non-dual, aged base RAF weight of 0.742. Under the older V24 model, I70.563 mapped to the same category but with a base RAF weight of 0.860, 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.

This code indicates bilateral involvement; ensure documentation confirms gangrene in both legs. Because I70.563 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 I70.563 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•This code indicates bilateral involvement; ensure documentation confirms gangrene in both legs.
•Bilateral gangrene is a serious condition; verify this is not a documentation error before coding.

Clinical Significance

This code captures atherosclerosis of a nonautologous biological bypass graft in the extremities complicated by gangrene, representing the most severe form of peripheral arterial disease with tissue necrosis. Gangrene indicates critical limb ischemia with irreversible tissue damage, often necessitating amputation and carrying significant mortality risk. Accurate capture is essential for risk adjustment as it reflects extremely high disease burden and resource utilization.

Documentation Requirements

✓Documentation of the type of bypass graft as nonautologous biological (must distinguish from autologous vein, nonautologous biological, or synthetic/nonbiological grafts)
✓Clinical evidence of atherosclerosis affecting the bypass graft (imaging, angiography, or clinical assessment)
✓Documentation of gangrene with description of extent and affected tissue
✓Assessment of the affected extremity including viability of surrounding tissue
✓Vascular study results (such as ankle-brachial index, arterial duplex, or angiography) demonstrating compromised graft flow
✓Documentation confirming bilateral involvement with findings described for each extremity

Commonly Confused Codes

•I70.4xx: Autologous vein bypass graft codes; use when the graft is the patient's own harvested vein, not donor or animal tissue
•I70.6xx: Nonbiological bypass graft codes; use when a synthetic graft material (such as Dacron or polytetrafluoroethylene) is used rather than biological tissue
•I70.2xx: Native artery atherosclerosis codes; use when no bypass graft is present and disease is in the patient's own arteries
•I70.52x: Atherosclerosis of same graft type with rest pain; use when there is critical ischemia pain but no tissue necrosis
•I96: Gangrene not elsewhere classified; use only when gangrene is not attributable to atherosclerosis or peripheral arterial disease
•E08.52-E13.52: Diabetic peripheral angiopathy with gangrene; use when gangrene is a complication of diabetes rather than bypass graft atherosclerosis