M45
Header — not billableAnkylosing spondylitis
The ICD-10 code for ankylosing spondylitis is M45.
M45 is a non-billable header code. It groups related conditions but cannot be used on its own for reimbursement — select one of the 11 more specific codes below.
Clinical notes
Excludes1 (not coded here)
An Excludes1 note is a pure exclusion: the excluded condition and this code should never be reported together, because the two conditions cannot occur at the same time (e.g. a congenital form vs. an acquired form of the same disease).
Excludes2 (not included here)
An Excludes2 note means the excluded condition is not part of this one, but a patient can have both at the same time — in that case both codes may be reported together.
- Behçet's disease (M35.2)
Also known as
Alternate wording, synonyms, or specific conditions that fall under this code, listed to help confirm you've picked the right one.
- Rheumatoid arthritis of spine
Documentation support
General coding-documentation guidance — not a substitute for payer-specific requirements or professional coding judgment.
- •This is a non-billable header code. Documentation must support a more specific child code before this diagnosis can be reported on a claim.
- •Confirm the excluded condition(s) listed above are not also present — Excludes1 conditions cannot be coded together with this one.
- •As a general rule, code to the highest level of specificity supported by the documentation in the medical record.
Child 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 spondyloarthritisnon-billable header