2026 ICD-10-CM Diagnosis Code M45.2Ankylosing spondylitis of cervical region

ICD-10-CM Codes›M00–M99›M45-M49›M45

ICD-10-CM M45.2
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

M45.2 is a billable ICD-10-CM diagnosis code for ankylosing spondylitis of cervical region. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 545 through 547. Coders also document this condition as cervical arthritis. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Rheumatoid arthritis and related disease and Spondylopathies/spondyloarthropathy (including infective).

Code Identity

ICD-10-CM Code
M45.2
Billable Status
Yes — Valid for Submission
Code Describes
Ankylosing spondylitis of cervical region
Short Description
Ankylosing spondylitis of cervical region
Same as the full description in the CMS dataset.
Parent Code
M45
Ankylosing spondylitis

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM45-M49Spondylopathies
CategoryM45Ankylosing spondylitis
This CodeM45.2Ankylosing spondylitis of cervical region

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Cervical arthritis
  • Inflammation of cervical spine joint
  • Rheumatoid arthritis of cervical spine
  • Rheumatoid arthritis of joint of spine

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.

    • Spondylitis(chronic)
      • ankylosing (chronic)
        • cervical region

Clinical ClassificationClinical

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

CCSR MUS003
Rheumatoid arthritis and related disease
Default principal diagnosis: inpatient No · outpatient No
CCSR MUS011
Spondylopathies/spondyloarthropathy (including infective)
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Ankylosing Spondylitis

Ankylosing spondylitis (AS) is a type of arthritis of the spine. It causes inflammation (swelling) between your vertebrae (the bones that make up your spine) and the joints between your spine and pelvis. AS inflammation can cause stiffness and make it difficult to move and bend.

The full article covers:

  • What is ankylosing spondylitis?
  • Who is more likely to get ankylosing spondylitis?
  • What causes ankylosing spondylitis?
  • What are the symptoms of ankylosing spondylitis?
  • How is ankylosing spondylitis diagnosed?
  • What are the treatments for ankylosing spondylitis?

Read the full article at MedlinePlus

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

Convert M45.2 to ICD-9-CMHistory

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

ICD-9-CM
720.0 Ankylosing spondylitis
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About M45.2Overview

Is M45.2 (Ankylosing spondylitis) a billable code?

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

What MS-DRG does M45.2 group to?

When ankylosing spondylitis of cervical region is the principal diagnosis on an inpatient stay, it groups to MS-DRG 545, 546, 547, with relative weights from 0.8362 to 2.4817 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of M45.2?

Under the General Equivalence Mappings, ankylosing spondylitis of cervical region converts to ICD-9-CM 720.0 (ankylosing spondylitis). 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.