2026 ICD-10-CM Diagnosis Code I71.21Aneurysm of the ascending aorta, without rupture

ICD-10-CM Codes›I00–I99›I70-I79›I71

ICD-10-CM I71.21
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

I71.21 is a billable ICD-10-CM diagnosis code for aneurysm of the ascending aorta, without rupture. 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 aneurysm of aortic root. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Aortic; peripheral; and visceral artery aneurysms.

Code Identity

ICD-10-CM Code
I71.21
Billable Status
Yes — Valid for Submission
Code Describes
Aneurysm of the ascending aorta, without rupture
Short Description
Aneurysm of the ascending aorta, without rupture
Same as the full description in the CMS dataset.
Parent Code
I71.2
Thoracic aortic aneurysm, without rupture

Code Classification

ChapterI00–I99Diseases of the circulatory system
SectionI70-I79Diseases of arteries, arterioles and capillaries
CategoryI71Aortic aneurysm and dissection
This CodeI71.21Aneurysm of the ascending aorta, without rupture

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Aneurysm of aortic root
  • Aneurysm of aortic sinus of Valsalva with protrusion into left ventricle
  • Aneurysm of aortic sinus of Valsalva with protrusion into pericardial cavity
  • Aneurysm of aortic sinus of Valsalva with protrusion into pulmonary artery
  • Aneurysm of aortic sinus of Valsalva with protrusion into right atrium
  • Aneurysm of aortic sinus of Valsalva with protrusion into right ventricle
  • Aneurysm of aortic sinus of Valsalva without rupture
  • Aneurysm of ascending aorta
  • Aortic sinus of Valsalva aneurysm from left coronary sinus
  • Aortic sinus of Valsalva aneurysm from right coronary sinus

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.

    • Aneurysm(anastomotic) (artery) (cirsoid) (diffuse) (false) (fusiform) (multiple) (saccular)
      • aorta, aortic (nonsyphilitic)
        • ascending
    • Aneurysm(anastomotic) (artery) (cirsoid) (diffuse) (false) (fusiform) (multiple) (saccular)
      • aorta, aortic (nonsyphilitic)
        • thorax, thoracic
          • ascending

Clinical ClassificationClinical

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

CCSR CIR029
Aortic; peripheral; and visceral artery aneurysms
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Aortic Aneurysm

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.

Code History & ChangesHistory

Replacement I71.21 replaces the following previously assigned code(s):

  • I71.2 - Thoracic aortic aneurysm, without rupture
FY 2023AddedAdded to the ICD-10-CM code setEffective October 1, 2022.
FY 2024–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About I71.21Overview

Is I71.21 (Thoracic aortic aneurysm, without rupture) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report aneurysm of the ascending aorta, without rupture on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does I71.21 group to?

When aneurysm of the ascending aorta, without rupture 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.

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.