2026 ICD-10-CM Diagnosis Code I77.70Dissection of unspecified artery

ICD-10-CM Codes›I00–I99›I70-I79›I77

ICD-10-CM I77.70
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

I77.70 is a billable ICD-10-CM diagnosis code for dissection of unspecified artery. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 299 through 301. Coders also document this condition as arterial dissection and lentiginosis syndrome. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Arterial dissections.

Code Identity

ICD-10-CM Code
I77.70
Billable Status
Yes — Valid for Submission
Code Describes
Dissection of unspecified artery
Short Description
Dissection of unspecified artery
Same as the full description in the CMS dataset.
Parent Code
I77.7
Other arterial dissection

Code Classification

ChapterI00–I99Diseases of the circulatory system
SectionI70-I79Diseases of arteries, arterioles and capillaries
CategoryI77Other disorders of arteries and arterioles
This CodeI77.70Dissection of unspecified artery

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Arterial dissection and lentiginosis syndrome
  • Cerebral ischemic stroke due to dissection of artery
  • Dissection of artery
  • Dissection of intracranial artery
  • Dissection of transplant artery

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Dissection
      • artery

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR CIR027
Arterial dissections
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Aneurysms

An aneurysm is a bulge or "ballooning" in the wall of an artery. Arteries are blood vessels that carry oxygen-rich blood from the heart to other parts of the body. If an aneurysm grows large, it can burst and cause dangerous bleeding or even death.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert I77.70 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
443.29 Dissection artery NEC
Approximate The match is approximate rather than exact.

Code History & ChangesHistory

Replacement I77.70 replaces the following previously assigned code(s):

  • I77.79 - Dissection of other artery
  • I77.79 - Dissection of other specified artery
FY 2018AddedAdded to the ICD-10-CM code setEffective October 1, 2017.
FY 2019–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About I77.70Overview

Is I77.70 (Other arterial dissection) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report dissection of unspecified artery on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does I77.70 group to?

When dissection of unspecified artery is the principal diagnosis on an inpatient stay, it groups to MS-DRG 299, 300, 301, with relative weights from 0.7197 to 1.6327 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of I77.70?

Under the General Equivalence Mappings, dissection of unspecified artery converts to ICD-9-CM 443.29 (dissection artery NEC). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.