What is ICD-10 code I70.55?

I70.55 is the ICD-10-CM diagnosis code for Atherosclerosis of nonautologous biological bypass graft(s) of other extremity with ulceration. Hardening of arteries in a biological bypass graft affecting other body parts (not the legs) with an open sore. I70.55 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. I70.55 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. I70.55 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. I70.55 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 I70.55?

I70.55 does not map to a payment HCC under either the CMS-HCC V28 risk adjustment model or the older V24 model. V28 reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition. Because neither model rewards I70.55 with a risk adjustment factor, it contributes zero to a Medicare Advantage beneficiary's RAF score in either version. Coders should check whether provider documentation supports a more specific child code that does map to a payment HCC.

What should coders know when reporting I70.55?

This code applies to extremities other than the legs; document which extremity is affected (arm, hand, etc.). Ensure the graft is nonautologous biological material and that ulceration is present.

I70.55 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 lookupI70.55Effective 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)

I70.55

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

Atherosclerosis of nonautologous biological bypass graft(s) of other extremity with ulceration

Hardening of arteries in a biological bypass graft affecting other body parts (not the legs) with an open sore.

Buddy Insight

CMS-HCC V28

Not risk-adjusted for this model/period.

RAF 0

CMS-HCC V24

Not risk-adjusted for this model/period.

RAF 0

ACA/HHS

Not risk-adjusted for this model/period.

RAF 0

ESRD/PACE

Not risk-adjusted for this model/period.

RAF 0

RXHCC

Mapped

HCC 311

Diabetic and Chronic Skin Ulcer

RAF 0.0

Code Trumping

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Compare selected patient codes to show trumped or trumps impact.

Code Book Path

Official

I70Atherosclerosis

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

I70.55Atherosclerosis of nonautologous biological bypass graft(s) of other extremity with ulceration

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for I70.55 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for I70.55 in this effective period.

Related Child Codes

Official

I70.50Unspecified atherosclerosis of nonautologous biological bypass graft(s) of the extremities

I70.51Atherosclerosis of nonautologous biological bypass graft(s) of the extremities intermittent claudication

I70.52Atherosclerosis of nonautologous biological bypass graft(s) of the extremities with rest pain

I70.53Atherosclerosis of nonautologous biological bypass graft(s) of the right leg with ulceration

I70.54Atherosclerosis of nonautologous biological bypass graft(s) of the left leg with ulceration

Includes

Official

any condition classifiable to I70.518, I70.528, and I70.538

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for I70.55 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for I70.55 in this effective period.

Use Additional

Official

code to identify severity of ulcer (L98.49)

Code Also

Official

ICD-10-CM does not list Code Also instructions for I70.55 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)

Description of the ulcer including location, size, depth, and wound bed characteristics

Documentation linking the ulceration to the atherosclerotic bypass graft disease

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)

Description of the ulcer including location, size, depth, and wound bed characteristics

Documentation linking the ulceration to the atherosclerotic bypass graft disease

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

Failing to assign an additional code for the specific ulcer site and severity from L97 category when applicable

Not linking the ulceration to the atherosclerotic graft disease — the causal relationship must be documented

Confusing venous stasis ulcers (I87.2 with L97) with arterial insufficiency ulcers caused by graft atherosclerosis

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

L97.xxx — Non-pressure chronic ulcer of lower limb; use when the ulcer is not caused by atherosclerotic disease

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 I70.55 an HCC code?

No. I70.55 is a billable ICD-10-CM code but does not map to any HCC category in V28, V24, ESRD, or RxHCC.

HCC Category Mapping

RxHCCHCC 311, Diabetic and Chronic Skin Ulcer

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 I70.55

For I70.55to 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 I70.55 during that encounter, not just copy-forwarded from a problem list.

What This Code Means

I70.55 is the ICD-10-CM diagnosis code for atherosclerosis of nonautologous biological bypass graft(s) of other extremity with ulceration. Hardening of arteries in a biological bypass graft affecting other body parts (not the legs) with an open sore. I70.55 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).

I70.55 is a billable ICD-10-CM code but does not map to a payment HCC under the CMS-HCC V28, V24, ESRD, or RxHCC risk adjustment models. It can be reported on Medicare Advantage encounter data submissions but it does not contribute to a beneficiary's RAF score and therefore does not affect risk-adjusted payments to the plan.

This code does not map to an HCC in the CMS-HCC V28 model, meaning it does not directly contribute to risk adjustment under the current payment model. It does not map to an HCC in the V24 model. Ulceration codes sit in the middle of the peripheral vascular disease severity hierarchy. In V28, HCC 264 is superseded by HCC 263 (gangrene) but represents significant vascular morbidity. In V24, HCC 108 is below HCC 106 (gangrene) and HCC 107 (ulceration with specific severity).

HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for I70.55 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•This code applies to extremities other than the legs; document which extremity is affected (arm, hand, etc.).
•Ensure the graft is nonautologous biological material and that ulceration is present.

Clinical Significance

This code identifies atherosclerosis of a nonautologous biological bypass graft with ulceration, representing advanced peripheral arterial disease where compromised blood flow has caused tissue breakdown. Ulceration in the setting of bypass graft atherosclerosis indicates graft failure or progression of disease beyond the graft, requiring aggressive wound care and potential revascularization. This diagnosis carries significant implications for patient morbidity and healthcare resource consumption.

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)
✓Description of the ulcer including location, size, depth, and wound bed characteristics
✓Documentation linking the ulceration to the atherosclerotic bypass graft disease
✓Vascular assessment results confirming arterial insufficiency as the cause
✓Documentation specifying which extremity is affected (for example, upper extremity)

Includes

any condition classifiable to I70.518, I70.528, and I70.538

Use Additional Code

code to identify severity of ulcer (L98.49)

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
•L97.xxx: Non-pressure chronic ulcer of lower limb; use when the ulcer is not caused by atherosclerotic disease
•L98.499: Non-pressure chronic ulcer of skin of other sites; use for ulcers unrelated to peripheral arterial disease