I73.9: Peripheral vascular disease, unspecified

The ICD-10-CM code for peripheral artery disease when the record documents peripheral vascular disease without a documented atherosclerotic cause. No code from the I70.2 to I70.7 family applies.

Billable

FY2027

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At a glance

Code Family

I70–I79: diseases of arteries, arterioles and capillaries, within chapter 9, diseases of the circulatory system.

DRG Grouping

MS-DRG 299, 300 or 301 in MDC 05 under the FY2027 MS-DRG v44 grouper, depending on complications and comorbidities. A qualifying O.R. vascular procedure moves the case to a surgical MS-DRG.

HCC Mapping (v28)

None: I73.9 was removed from HCC mapping in CMS-HCC v28. It mapped to HCC 108, vascular disease, under v24.

Condition

Peripheral artery disease

Family Specificity

I73.9 is the unspecified peripheral vascular disease code. Raynaud's syndrome codes to I73.00 or I73.01, thromboangiitis obliterans to I73.1, and atherosclerotic disease of the extremities to the I70.2 to I70.7 family.

Billable

Yes: valid for HIPAA-covered transactions in the FY2027 code set.

Which I73 code do I assign?

I73.9 is the residual code for peripheral vascular disease, and it is appropriate only when the vascular disease is non-atherosclerotic or the etiology is genuinely unspecified. Once atherosclerosis is documented as the cause, the I70.2 to I70.7 family applies instead. I73.9 carries an Excludes1 note for atherosclerosis of the extremities, and the two are not reported together for the same condition.

When documentation says…

Code

Atherosclerotic peripheral vascular disease with gangrene

I70.26- Atherosclerosis of native arteries of extremities with gangrene. The record must name atherosclerosis as the etiology, the affected extremity and the complication. With gangrene, the I70.26- codes map to HCC 263 in v28.

Atherosclerotic peripheral vascular disease with ulceration

I70.23- Atherosclerosis of native arteries of right leg with ulceration, with I70.24- for the left leg and I70.25 for other extremities. The ulcer site and the laterality both have to be documented. With ulceration, the I70.23- to I70.25 codes map to HCC 263 in v28.

Atherosclerosis of native arteries of the extremities with intermittent claudication

I70.21-

Assign when claudication is documented and atherosclerosis is named as its cause, rather than treating the claudication as unspecified peripheral vascular disease.

Raynaud's syndrome with gangrene

I73.01

The record must document Raynaud's syndrome and the presence of gangrene.

Raynaud's syndrome without gangrene

I73.00

Raynaud's syndrome documented with no gangrene present.

Thromboangiitis obliterans, or Buerger's disease

I73.1

Assign when the provider documents thromboangiitis obliterans by name.

Peripheral vascular disease, peripheral angiopathy or spasm of artery with no atherosclerotic cause documented

I73.9

The residual code, correct only when the vascular disease is non-atherosclerotic or the etiology is not characterized in the record. When diabetes is documented, the Index sends peripheral vascular disease to the diabetes combination codes, such as E11.51.

Tabular notes

INCLUDES

Intermittent claudication, peripheral angiopathy NOS and spasm of artery are inclusion terms at I73.9.

EXCLUDES1

Atherosclerotic peripheral vascular disease, I70.2 to I70.7. When atherosclerosis is documented as the etiology of the peripheral vascular disease, codes from the I70.2 to I70.7 family apply and cannot be reported together with I73.9 for the same anatomical territory.

EXCLUDES2: INHERITED FROM CATEGORY I73

Chilblains (T69.1), frostbite (T33-T34), immersion hand or foot (T69.0-) and spasm of cerebral artery (G45.9). An Excludes2 note means the excluded condition is not part of I73.9. Both codes may be reported when both conditions are documented.

USE ADDITIONAL AND CODE FIRST

I73.9 carries no Use Additional or Code First instruction in FY2027, and none sits at category I73 or block I70-I79.

FY2027 CODE CHANGES

The FY2027 codes addenda make no addition, deletion or revision in category I73 or category I70. The FY2027 tabular addenda make no change to the I73 or I73.9 notes. I73.9 is unchanged in the FY2027 update.

Operational & financial impact

Why specificity matters beyond the chart: risk adjustment, DRG assignment and denial exposure all follow from which code is selected.

CMS-HCC v28 (PY2024+)

No HCC mapping applies to I73.9. CMS removed unspecified peripheral vascular disease from risk adjustment in v28.

Under CMS-HCC v24, I73.9 mapped to HCC 108, vascular disease. The v24 to v28 transition is where the weight was lost.

In v28, atherosclerosis of the extremities with rest pain (I70.22- and the matching graft codes) maps to HCC 264: Vascular Disease with Complications. With ulceration or gangrene, it maps to HCC 263: Atherosclerosis of Arteries of the Extremities with Ulceration or Gangrene. Unspecified atherosclerosis of the extremities and atherosclerosis with intermittent claudication map to no v28 HCC. Outside I70, I73.01, Raynaud's syndrome with gangrene, also maps to HCC 263.

MS-DRG v44 (FY2027)

As the principal inpatient diagnosis, I73.9 groups to MDC 05 under the FY2027 MS-DRG v44 grouper. The case groups to MS-DRG 299, peripheral vascular disorders with MCC; MS-DRG 300, peripheral vascular disorders with CC; or MS-DRG 301, peripheral vascular disorders without CC/MCC. A qualifying O.R. vascular procedure moves the case to a surgical MS-DRG.

Medicare and commercial payers

I73.9 is valid for Medicare claims.

Documentation checklist to support I73.9

Chart elements that support code selection and reduce specificity-driven denials.

A stated diagnosis of peripheral vascular disease, peripheral angiopathy, intermittent claudication as a vascular diagnosis, or spasm of artery.

Whether an atherosclerotic cause is documented, because atherosclerotic peripheral vascular disease codes to I70.2 through I70.7 and cannot be reported as I73.9.

The anatomical site and laterality: right leg, left leg or bilateral, when atherosclerosis is the documented etiology.

Any complication of the atherosclerotic disease, including rest pain, ulceration or gangrene, since the complication is what enables HCC capture under v28.

Whether the presentation is a distinct named entity such as Raynaud's syndrome or thromboangiitis obliterans, which carry their own codes within I73.

The results of ankle-brachial index testing or vascular imaging when they characterize the disease. The code can be updated from I73.9 to the specific atherosclerosis code.

FAQ

Does I73.9 still carry HCC weight in 2026?

No. I73.9 was removed from HCC mapping in CMS-HCC v28. Under CMS-HCC v24 the code mapped to HCC 108, vascular disease. The move to v28 eliminated unspecified peripheral vascular disease from risk adjustment.

What is the HCC capture path for peripheral artery disease under v28?

Capture requires documentation of atherosclerosis with specific complications. Atherosclerosis of the extremities with rest pain maps to HCC 264, and atherosclerosis with ulceration or gangrene maps to HCC 263. Unspecified atherosclerosis of the extremities and atherosclerosis with intermittent claudication map to no v28 HCC. I73.9 itself does not participate in this capture. The record needs the atherosclerotic etiology, the site and the complication for the encounter to be coded from the I70.2 to I70.7 family.

Can I73.9 be reported together with atherosclerosis of the extremities?

No. An Excludes1 note prohibits reporting I73.9 with I70.2 to I70.7 for the same condition. When the record documents atherosclerotic peripheral vascular disease, the atherosclerosis code applies on its own and I73.9 is not added.

How should intermittent claudication be coded?

Intermittent claudication appears as an Includes term at I73.9. Claudication without an identified atherosclerotic cause may be coded there. When the provider documents the claudication as atherosclerotic, the specific code for atherosclerosis of native arteries with intermittent claudication, I70.21-, applies instead.

If a patient has both Raynaud's syndrome and atherosclerotic peripheral vascular disease, which code applies?

These are distinct conditions and both may be coded when each is independently documented. Raynaud's syndrome is reported as I73.00 without gangrene or I73.01 with gangrene, and the atherosclerotic disease is reported from I70.2 to I70.7. I73.9 does not apply when both of the more specific codes are available.

When is I73.9 a principal or a secondary diagnosis?

In the outpatient setting it is appropriate for vascular follow-up when the type and etiology of the peripheral vascular disease have not been fully characterized. Inpatient, Section II makes it principal only when it is the condition established after study to be chiefly responsible for the admission. When a patient is admitted for a vascular procedure such as angioplasty or bypass, the procedural MS-DRG grouping drives assignment and the vascular diagnosis supports the indication.

Related codes

Codes in the same family as I73.9. Only codes with a published page render as links.

Sibling codes in the I73 family

I73.00: Raynaud's syndrome without gangrene.
I73.01: Raynaud's syndrome with gangrene.
I73.1: Thromboangiitis obliterans [Buerger's disease].
I73.9: Peripheral vascular disease, unspecified.

Additional codes to consider

Codes outside the I73 family considered alongside I73.9.

Consider instead

I70.2–I70.7: Atherosclerosis of arteries of the extremities. Use instead of I73.9 whenever atherosclerosis is the documented etiology.
I70.21-: Atherosclerosis of native arteries of extremities with intermittent claudication. Use instead of I73.9 when the claudication is documented as atherosclerotic.
T69.1XX-: Chilblains. Listed in the category I73 Excludes2 note and classified to the injury chapter.
T33–T34: Frostbite. Listed in the category I73 Excludes2 note and classified to the injury chapter.
T69.0-: Immersion hand and foot. Listed in the category I73 Excludes2 note and classified to the injury chapter.
E11.51: Type 2 diabetes mellitus with diabetic peripheral angiopathy without gangrene. Use instead of I73.9 when type 2 diabetes is documented with peripheral vascular disease.

Sources

All claims on this page derive from government and professional-standards sources.

National Center for Health Statistics. (2026). International classification of diseases, tenth revision, clinical modification (ICD-10-CM) FY2027 files. https://www.cdc.gov/nchs/icd/icd-10-cm/files.html
Centers for Medicare & Medicaid Services and National Center for Health Statistics. (2026). ICD-10-CM official guidelines for coding and reporting FY2027. https://ftp.cdc.gov/pub/Health_Statistics/NCHS/Publications/ICD10CM/2027/ICD-10-CM-October-1-2026-FY27-Guidelines.pdf
Centers for Medicare & Medicaid Services. (2025). 2026 model software/ICD-10 mappings. https://www.cms.gov/medicare/payment/medicare-advantage-rates-statistics/risk-adjustment/2026-model-software-icd-10-mappings
Centers for Medicare & Medicaid Services. (2026). MS-DRG classifications and software, version 44. https://www.cms.gov/medicare/payment/prospective-payment-systems/acute-inpatient-pps/ms-drg-classifications-and-software