2027 ICD-10-CM Diagnosis Code M45Ankylosing spondylitis

ICD-10-CM Codes›M00–M99›M45-M49›M45

ICD-10-CM M45
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

M45 is a non-billable ICD-10-CM category code for ankylosing spondylitis, so it cannot be submitted on claims. Use a more specific code from this category instead, such as M45.0, M45.1, M45.2, and M45.3.

Code Identity

ICD-10-CM Code
M45
Billable Status
No — Non-Billable Category
Code Describes
Ankylosing spondylitis
Short Description
Ankylosing spondylitis
Same as the full description in the CMS dataset.
Chapter
M45-M49
Spondylopathies

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM45-M49Spondylopathies
CategoryM45Ankylosing spondylitis
This CodeM45Ankylosing spondylitis

Specific Coding for Ankylosing spondylitisOverview

Non-specific codes like M45 require more characters. Use one of these billable codes instead:

  • Use M45.0 for Ankylosing spondylitis of multiple sites in spine

  • Use M45.1 for Ankylosing spondylitis of occipito-atlanto-axial region

  • Use M45.2 for Ankylosing spondylitis of cervical region

  • Use M45.3 for Ankylosing spondylitis of cervicothoracic region

  • Use M45.4 for Ankylosing spondylitis of thoracic region

  • Use M45.5 for Ankylosing spondylitis of thoracolumbar region

  • Use M45.6 for Ankylosing spondylitis lumbar region

  • Use M45.7 for Ankylosing spondylitis of lumbosacral region

  • Use M45.8 for Ankylosing spondylitis sacral and sacrococcygeal region

  • Use M45.9 for Ankylosing spondylitis of unspecified sites in spine

  • M45.A for Non-radiographic axial spondyloarthritis

  • Use M45.A0 for Non-radiographic axial spondyloarthritis of unspecified sites in spine

  • Use M45.A1 for Non-radiographic axial spondyloarthritis of occipito-atlanto-axial region

  • Use M45.A2 for Non-radiographic axial spondyloarthritis of cervical region

  • Use M45.A3 for Non-radiographic axial spondyloarthritis of cervicothoracic region

  • Use M45.A4 for Non-radiographic axial spondyloarthritis of thoracic region

  • Use M45.A5 for Non-radiographic axial spondyloarthritis of thoracolumbar region

  • Use M45.A6 for Non-radiographic axial spondyloarthritis of lumbar region

  • Use M45.A7 for Non-radiographic axial spondyloarthritis of lumbosacral region

  • Use M45.A8 for Non-radiographic axial spondyloarthritis of sacral and sacrococcygeal region

  • Use M45.AB for Non-radiographic axial spondyloarthritis of multiple sites in spine

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to M45: its own notes plus those printed at Chapter 13. A note printed at a category, block or chapter applies to every code under it.

Applicable To

Conditions this code is used for: synonyms of the title or, for "other specified" codes, the conditions assigned to it. The list is not exhaustive.

  • Rheumatoid arthritis of spine

Excludes1

Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.

  • arthropathy in Reiter's disease (M02.3-)
  • juvenile (ankylosing) spondylitis (M08.1)

Excludes2

Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.

On M45 itself
  • Behçet's disease (M35.2)
From Chapter 13 (M00-M99) Diseases of the musculoskeletal system and connective tissue applies to 6,687 codes
  • arthropathic psoriasis (L40.5-)
  • certain conditions originating in the perinatal period (P04-P96)
  • certain infectious and parasitic diseases (A00-B99)
  • compartment syndrome (traumatic) (T79.A-)
  • complications of pregnancy, childbirth and the puerperium (O00-O9A)
  • congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
  • endocrine, nutritional and metabolic diseases (E00-E88)
  • injury, poisoning and certain other consequences of external causes (S00-T88)
  • neoplasms (C00-D49)
  • symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)

Notes

General instructions on how these codes are used.

From Chapter 13 (M00-M99) Diseases of the musculoskeletal system and connective tissue applies to 6,687 codes
  • Use an external cause code following the code for the musculoskeletal condition, if applicable, to identify the cause of the musculoskeletal condition

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name M45, its category, or a range that includes it.

Excludes1 2

These codes carry an Excludes1 note naming M45: they are not reported together with it, unless the two conditions are unrelated.

  • G55 Nerve root and plexus compressions in diseases classified elsewhere
    nerve root compression (due to) (in) ankylosing spondylitis (M45.-)
  • M05 Rheumatoid arthritis with rheumatoid factor
    rheumatoid arthritis of spine (M45.-)

Code First 1

These codes say to code first a condition named in the note, and M45 is one of the conditions named.

  • J99 Respiratory disorders in diseases classified elsewhere
    ankylosing spondylitis (M45.-)

Clinical InformationClinical

  • Spondylitis, Ankylosing

    a chronic inflammatory condition affecting the axial joints, such as the sacroiliac joint and other intervertebral or costovertebral joints. it occurs predominantly in young males and is characterized by pain and stiffness of joints (ankylosis) with inflammation at tendon insertions.

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.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About M45Overview

What is the ICD-10 code for ankylosing spondylitis?

M45 is the ICD-10-CM category for ankylosing spondylitis, but it is a non-billable header: claims need a more specific code from this category, listed on this page.

Is M45 (Ankylosing spondylitis) a billable code?

No. This is a category header that groups the codes for ankylosing spondylitis, and headers cannot be submitted on claims. Claims for ankylosing spondylitis need a more specific code from this category, such as M45.0, M45.1, and M45.2.

Can M45 be reported with a code from M02.3?

Not as a rule. The Excludes1 note on M45 lists "arthropathy in Reiter's disease (M02.3-)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).