I70.599 ICD-10-CM Code: Other atherosclerosis of nonautologous biological bypass graft(s) of the extremities, unspecified extremity
HCC Buddy Code Card
Digital ICD-10 code-book layout with official code detail, always-visible risk models, Code Trumping, and Buddy coding guidance.
FY 2026 Apr update / Diseases of the circulatory system (I00-I99) / Diseases of arteries, arterioles and capillaries (I70-I79)
I70.599
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceOther atherosclerosis of nonautologous biological bypass graft(s) of the extremities, unspecified extremity
Hardening of arteries in a surgically placed biological bypass graft in an unspecified extremity, without gangrene or other specified complications.
Buddy Insight
This code captures other specified manifestations of atherosclerosis in a nonautologous biological bypass graft, covering presentations that do not fit the specific categories of claudication, rest pain, ulceration, or gangrene.
CMS-HCC V28
00
RAF 0
CMS-HCC V24
MappedHCC 108
RAF 0.297
ACA/HHS
00
RAF 0
ESRD/PACE
MappedHCC 108
RAF 0.0
RXHCC
00
RAF 0
Code Trumping
Basket needed
Code Book Path
Inclusion Terms
OfficialICD-10-CM does not list inclusion terms for I70.599 in this effective period.
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for I70.599 in this effective period.
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for I70.599 in this effective period.
Excludes 1
OfficialICD-10-CM does not list Excludes 1 notes for I70.599 in this effective period.
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for I70.599 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for I70.599 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for I70.599 in this effective period.
Buddy Documentation Tip
MEAT Support
Audit Caution
Common Mistakes
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 I70.599 an HCC code?
Yes. I70.599 maps to Vascular Disease under the V24 model but is not retained in V28.
HCC Category Mapping
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 I70.599
For I70.599to 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 I70.599 during that encounter, not just copy-forwarded from a problem list.
What This Code Means
I70.599 is the ICD-10-CM diagnosis code for other atherosclerosis of nonautologous biological bypass graft(s) of the extremities, unspecified extremity. Hardening of arteries in a surgically placed biological bypass graft in an unspecified extremity, without gangrene or other specified complications. I70.599 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, I70.599 maps to Vascular Disease (HCC 108) with a community, non-dual, aged base RAF weight of 0.297. 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 is a less specific code; attempt to query the provider for the exact extremity location. Because I70.599 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 I70.599 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •This is a less specific code; attempt to query the provider for the exact extremity location
- •Use only when the extremity cannot be determined from available documentation
Clinical Significance
This code captures other specified manifestations of atherosclerosis in a nonautologous biological bypass graft, covering presentations that do not fit the specific categories of claudication, rest pain, ulceration, or gangrene. These may include conditions such as atheroembolism from the graft, aneurysmal degeneration, or other vascular complications requiring clinical attention. Proper code selection ensures that the full spectrum of peripheral arterial disease severity is captured for risk adjustment.
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)
- ✓Specific description of the atherosclerotic manifestation that does not fit claudication, rest pain, ulceration, or gangrene categories
- ✓Vascular assessment supporting the diagnosis
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