I65.29: Occlusion and stenosis of unspecified carotid artery

The ICD-10-CM code for carotid artery stenosis, occlusion or atherosclerosis that has not resulted in cerebral infarction, when the record does not identify the right, left or both carotid arteries.

Billable

FY2027

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At a glance

Code Family

I65.2: Occlusion and stenosis of carotid artery.

DRG Grouping

MS-DRG 067 or 068, Precerebral occlusion without infarction, when I65.29 is the principal diagnosis under the FY2027 MS-DRG v44 grouper.

HCC Mapping (v28)

None. I65.29 is absent from the CMS-HCC v28 diagnosis crosswalk.

Family Specificity

Four billable codes sit in I65.2, split only by side. I65.29 is the code for a carotid artery the record never identifies by side.

Billable

Yes. I65.29 is a complete code in the FY2027 billable code list.

Effective Date

Valid in the FY2026 code set and unchanged in the FY2027 update.

Which I65.2 code do I assign?

Subcategory I65.2 splits carotid occlusion and stenosis by side only: right, left, bilateral or unspecified. Category I65 excludes lesions that result in cerebral infarction, which the Index sends to category I63 instead.

When documentation says…

Code

Carotid stenosis, side not documented

I65.29

Occlusion and stenosis of unspecified carotid artery. The Index sends Occlusion, artery, carotid and Arteriosclerosis, carotid to the I65.2 codes. Use I65.29 only when no clinician in the record names the side and the provider cannot clarify.

Right internal carotid artery stenosis

I65.21

Occlusion and stenosis of right carotid artery. The note names the right side. Guideline I.B.13 allows the side to come from another clinician's documentation in the record.

Left carotid occlusion

I65.22

Occlusion and stenosis of left carotid artery. The note names the left side. Category I65 includes complete and partial obstruction. A fully occluded left carotid stays here.

Bilateral carotid stenosis

I65.23

Occlusion and stenosis of bilateral carotid arteries. Report the single bilateral code. Guideline I.B.13 calls for separate right and left codes only when no bilateral code is provided.

Stroke with carotid stenosis, side not stated

I63.239

Cerebral infarction due to unspecified occlusion or stenosis of unspecified carotid artery. The Index lists infarction under with at Occlusion, artery, carotid. Guideline I.A.15 presumes the causal link unless the documentation clearly states the conditions are unrelated.

Carotid bruit, duplex pending

R09.89

Other specified symptoms and signs involving the circulatory and respiratory systems. Bruit (arterial) is an inclusion term at R09.89. Once an interpreted study confirms the stenosis, Section IV.K codes the confirmed diagnosis and not related signs.

Carotid artery insufficiency

G45.1

Carotid artery syndrome (hemispheric). The Index sends Insufficiency, arterial, carotid to G45.1. The I65 Excludes1 note names insufficiency, NOS, of precerebral artery (the G45 codes).

Tabular notes

INCLUDES

Category I65 includes embolism, narrowing, obstruction (complete) (partial) and thrombosis of precerebral artery. I65.29 and its subcategory I65.2 carry no inclusion terms of their own.

EXCLUDES1

Category I65 carries an Excludes1 note for insufficiency, NOS, of precerebral artery (G45.-) and for insufficiency of precerebral arteries causing cerebral infarction (I63.0-I63.2). Neither is reported with I65.29 for the same condition.

The I60-I69 block adds an Excludes1 note for traumatic intracranial hemorrhage (the S06 codes).

Guideline I.A.12.a allows an Excludes1 pair when the two conditions are unrelated to each other. If it is not clear whether they are related, the guideline says to query the provider.

EXCLUDES2

Chapter 9 carries an Excludes2 note for transient cerebral ischemic attacks and related syndromes (the G45 codes). A TIA documented with a carotid stenosis may take both codes when the patient has both conditions.

The same chapter note also names systemic connective tissue disorders (M30-M36), neoplasms (C00-D49), injury, poisoning and certain other consequences of external causes (S00-T88), and symptoms, signs and abnormal clinical and laboratory findings (R00-R94), among other chapters.

USE ADDITIONAL

The I60-I69 block carries a use additional code note to identify presence of alcohol abuse and dependence (F10.-), exposure to environmental tobacco smoke (Z77.22), history of tobacco dependence (Z87.891), hypertension (I10-I1A), occupational exposure to environmental tobacco smoke (Z57.31), tobacco dependence (F17.-) and tobacco use (Z72.0).

The note sits on the block and reaches I65.29 from there. Guideline I.B.7 states that a use additional code note indicates a secondary code should be added, if known.

CODE FIRST

I65.29 carries no code first or code also instruction. None sits above it at I65.2, I65, the I60-I69 block or Chapter 9.

FY2027: EFFECTIVE 1 OCTOBER 2026

The FY2027 codes addenda make no addition, deletion or revision in categories I63, I65 or I66. I65.29 is in the FY2027 billable code list and is unchanged in the FY2027 update.

The I65 Includes and Excludes1 notes and the I60-I69 block notes read the same in the FY2027 tabular as in the April 2026 FY2026 tabular.

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 code in category I65 maps to a payment HCC in the CMS-HCC v28 diagnosis crosswalk.

In the same crosswalk, the cerebral infarction codes for the carotid artery in subcategories I63.03, I63.13 and I63.23 all map to HCC 249: Ischemic or Unspecified Stroke.

MS-DRG v44 (FY2027)

MS-DRG 067: Precerebral occlusion without infarction with MCC.

MS-DRG 068: Precerebral occlusion without infarction without MCC.

MS-DRG 061: Ischemic stroke, precerebral occlusion or transient ischemia with thrombolytic agent with MCC.

MS-DRG 062: Ischemic stroke, precerebral occlusion or transient ischemia with thrombolytic agent with CC.

MS-DRG 063: Ischemic stroke, precerebral occlusion or transient ischemia with thrombolytic agent without CC/MCC.

I65.29 as principal diagnosis groups to MS-DRG 067 or 068 in MDC 01, per the CMS MS-DRG v44.0 Definitions Manual, Appendix B. The same appendix lists it under MS-DRG 061 to 063 for stays with a thrombolytic agent.

WHERE SPECIFICITY IS LOST

Reporting I65.29 when another clinician's documentation in the record names the side leaves a supported laterality uncoded. Guideline I.B.13 states that codes for unspecified side should rarely be used.

Reporting I65.29 for a carotid occlusion that caused an infarct contradicts the I65 title, which reads not resulting in cerebral infarction. It also omits the I63 code, which maps to HCC 249.

Carotid dissection indexes to I77.71 and carotid artery insufficiency to G45.1. Reporting I65.29 for either replaces the code the Index assigns.

SEVERITY DESIGNATION (MS-DRG V44, FY2027)

I65.29 is on neither list. It carries no CC or MCC designation as a secondary diagnosis.

No code in subcategory I65.2 carries a CC or MCC designation.

Per Table 6I (Complete MCC List) and Table 6J (Complete CC List) of the FY2027 IPPS final rule (CMS-1849-F), MS-DRG v44.

Documentation checklist to support I65.29

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

The artery and side in the provider's words. A named right, left or bilateral carotid moves the code to I65.21, I65.22 or I65.23.

The side from another clinician's documentation when the provider omits it, as Guideline I.B.13 allows, or a provider query when the record conflicts.

A statement of whether a cerebral infarction is present. A carotid occlusion with infarction indexes to category I63, not to I65.

The lesion in the provider's words. The Index routes carotid occlusion, narrowing, thrombosis, embolism, plaque and arteriosclerosis to the I65.2 codes. The I65.2 title names stenosis.

For an outpatient duplex, CT angiogram or angiogram, the interpreted final report with the confirmed diagnosis (Section IV.K).

Hypertension, tobacco dependence or use, history of tobacco dependence, tobacco smoke exposure and alcohol abuse or dependence, which the I60-I69 use additional code note asks to be coded.

Any prior TIA or stroke without residual deficits, which adds Z86.73 when the history affects current care (Section IV.J).

For outpatient encounters, a confirmed stenosis rather than a probable, suspected or rule out diagnosis (Section IV.H).

FAQ

Is I65.29 a billable code?

Yes. I65.29 is a complete code with no further characters. It appears in the FY2027 billable code list. Its parents I65.2 and I65 are headers and cannot be reported.

What is the ICD-10 code for carotid stenosis?

Carotid stenosis is coded in subcategory I65.2 by side: I65.21 right, I65.22 left, I65.23 bilateral and I65.29 unspecified. The Index has no carotid subterm directly under Stenosis. Stenosis, artery NEC, precerebral says see Occlusion, artery, precerebral, whose carotid subterm says see Occlusion, artery, carotid. That entry goes to the I65.2 codes. Narrowing, Thrombosis, Embolism and Arteriosclerosis, carotid lead there as well.

What is the ICD-10 code for carotid artery disease?

The Index has no entry for carotid artery disease. Disease, artery indexes to I77.9 and lists no carotid subterm. Code the lesion the provider documents. Carotid occlusion, plaque and arteriosclerosis index to the I65.2 codes. The I65.2 title names stenosis. Carotid dissection indexes to I77.71.

What is the difference between I65.29 and I63.239?

The difference is infarction. I65.29 is carotid occlusion or stenosis not resulting in cerebral infarction. I63.239 is cerebral infarction due to unspecified occlusion or stenosis of unspecified carotid artery. The Index lists infarction under with at Occlusion, artery, carotid. Guideline I.A.15 presumes the causal link unless the documentation clearly states the conditions are unrelated.

Does I65.29 map to an HCC under CMS-HCC v28?

No. I65.29 is absent from the CMS-HCC v28 diagnosis crosswalk. No other I65 code appears in it. In the same crosswalk, the cerebral infarction codes for carotid occlusion or stenosis, such as I63.239, map to HCC 249, Ischemic or Unspecified Stroke.

Can I65.29 be reported with a TIA or a history of stroke?

Chapter 9 carries an Excludes2 note for transient cerebral ischemic attacks and related syndromes (the G45 codes). That note allows a current TIA code such as G45.9 with I65.29 when both are documented. A past TIA or stroke without residual deficits is Z86.73, which may be added when it affects current care (Section IV.J). Guideline I.C.9.d.3 bars I69 codes when the patient has no neurologic deficits.

How is I65.29 sequenced in inpatient and outpatient settings?

For an outpatient carotid study, Section IV.K sequences first the condition chiefly responsible for the service. Once the interpreted report confirms the stenosis, it codes that diagnosis and not related signs such as a bruit. A probable or suspected stenosis is not coded outpatient (Section IV.H). In the inpatient setting, an uncertain diagnosis documented at discharge is coded as if it existed (Section II.H).

What changed for I65.29 in FY2027?

Nothing in the code set. The FY2027 codes addenda make no addition, deletion or revision in categories I63, I65 or I66. The I65 and I60-I69 block notes read the same as in the FY2026 tabular. I65.29 remains a billable code.

Related codes

Codes in the same family as I65.29. Only codes with a published page render as links.

Sibling codes in the I65.2 family

I65.21: Occlusion and stenosis of right carotid artery, when the record names the right side.
I65.22: Occlusion and stenosis of left carotid artery, when the record names the left side.
I65.23: Occlusion and stenosis of bilateral carotid arteries, when both carotid arteries are affected.

Additional codes to consider

Codes outside the I65.2 family considered alongside I65.29.

Companion: code alongside when documented

I10: Essential (primary) hypertension, under the I60-I69 use additional code note.
F17: Nicotine dependence, when tobacco dependence is documented.
Z72.0: Tobacco use, when tobacco use without dependence is documented.
Z87.891: Personal history of nicotine dependence, when a history of tobacco dependence is documented.
Z77.22: Contact with and (suspected) exposure to environmental tobacco smoke (acute) (chronic), when exposure is documented.
Z57.31: Occupational exposure to environmental tobacco smoke, when workplace exposure is documented.
F10: Alcohol related disorders, when alcohol abuse or dependence is documented.

Consider instead

I63.239: Cerebral infarction due to unspecified occlusion or stenosis of unspecified carotid artery, when a cerebral infarction is documented with the carotid lesion.
I63.039: Cerebral infarction due to thrombosis of unspecified carotid artery, when the infarction is due to carotid thrombosis.
I63.139: Cerebral infarction due to embolism of unspecified carotid artery, when the infarction is due to carotid embolism.
I65.9: Occlusion and stenosis of unspecified precerebral artery, when the provider documents precerebral artery occlusion without naming the artery.
I65.09: Occlusion and stenosis of unspecified vertebral artery, when the narrowed vessel is a vertebral artery.
I66.9: Occlusion and stenosis of unspecified cerebral artery, when the narrowed vessel is a cerebral artery.
I67.2: Cerebral atherosclerosis, when cerebral arteriosclerosis is documented without a carotid site.
G45.1: Carotid artery syndrome (hemispheric), when carotid artery insufficiency is documented.
I77.71: Dissection of carotid artery, when the provider documents a carotid dissection.
R09.89: Other specified symptoms and signs involving the circulatory and respiratory systems, when a carotid bruit is documented without a confirmed stenosis.

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