Is M45 a billable ICD-10-CM code?

No. M45 is a non-billable header code. Code to a higher level of specificity using one of its child codes.

Where does M45 sit in the tabular list?

Diseases of the musculoskeletal system and connective tissue (M00-M99), in the block Spondylopathies (M45-M49).

What cannot be coded together with M45?

M45 carries an Excludes1 note, which means the conditions it lists can never be coded together with it on the same encounter.

M45

M45 — Ankylosing spondylitis

Non-billable headerICD-10-CM

M45 is a non-billable header ICD-10-CM code for ankylosing spondylitis. It cannot be billed on its own: choose one of the more specific child codes below.

Excludes1 — never code together

These conditions cannot occur together. Billing both on the same encounter is a denial.

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

Excludes2 — not included here, but may coexist

The excluded condition is not part of this code, but a patient can have both. You may code both.

Behçet's disease (M35.2)

Inclusion terms

Alternative wordings a physician may use in the chart for this same code.

Rheumatoid arthritis of spine

Other codes that can never be billed with M45

These codes carry an Excludes1 note pointing at M45. The conflict binds both ways, but ICD-10-CM only writes it down on one side — so you would not find this by reading M45 alone.

M05Rheumatoid arthritis with rheumatoid factor
M08.1Juvenile ankylosing spondylitis
M43.2Fusion of spine
G55Nerve root and plexus compressions in diseases classified elsewhere

Risk adjustment

M45 does not map to an HCC and does not risk-adjust under CMS-HCC V28. That is normal — most ICD-10 codes do not. It still needs to be coded correctly; it just will not move a RAF score.

Code to one of these instead M45

11 child codes. Green means billable.

Questions about M45

Is M45 a billable ICD-10-CM code?: No. M45 is a non-billable header code. Code to a higher level of specificity using one of its child codes.
Where does M45 sit in the tabular list?: Diseases of the musculoskeletal system and connective tissue (M00-M99), in the block Spondylopathies (M45-M49).
What cannot be coded together with M45?: M45 carries an Excludes1 note, which means the conditions it lists can never be coded together with it on the same encounter.