M45
ICD-10Non-billable categoryAnkylosing spondylitis
Official ICD-10-CM descriptor (FY2026)
Ankylosing spondylitis
M45 is a category heading, not a billable code. CMS does not accept it on a claim; report one of the more specific codes beneath it.
Inclusion terms
- Rheumatoid arthritis of spine
Excludes1
Not coded here. An Excludes1 code should never be reported at the same time as the code above it.
- arthropathy in Reiter's disease (M02.3-)
- juvenile (ankylosing) spondylitis (M08.1)
Excludes2
Not included here. The condition is not part of this code, but a patient may have both, and both codes may be reported together.
- Behçet's disease (M35.2)
More specific codes under M45
- M45.0Ankylosing spondylitis of multiple sites in spine
- M45.1Ankylosing spondylitis of occipito-atlanto-axial region
- M45.2Ankylosing spondylitis of cervical region
- M45.3Ankylosing spondylitis of cervicothoracic region
- M45.4Ankylosing spondylitis of thoracic region
- M45.5Ankylosing spondylitis of thoracolumbar region
- M45.6Ankylosing spondylitis lumbar region
- M45.7Ankylosing spondylitis of lumbosacral region
- M45.8Ankylosing spondylitis sacral and sacrococcygeal region
- M45.9Ankylosing spondylitis of unspecified sites in spine
- M45.ANon-radiographic axial spondyloarthritiscategory
Where this code sits
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ICD-10-CM FY2026. Centers for Medicare & Medicaid Services (CMS) / National Center for Health Statistics (NCHS), “2026 ICD-10-CM Code Descriptions in Tabular Order” (icd10cm_order_2026.txt). Download the original file from cms.gov. Public domain (US Government work). Descriptors, billable flags and instructional notes on this page are reproduced from that file without modification. Krasyn adds no clinical guidance.