Bacterial or other microbial infection of vertebral bone at the cervicothoracic junction (C7–T1 transition zone), classified under other inflammatory spondylopathies.
Verified May 8, 2026 · 5 sources ↓
- Status
- Billable
- Chapter
- 13
- Related CPT
- 12
- Region
- Spine
Documentation tips
What should appear in the chart to support M46.23.
Source · Editorial brief grounded in 5 cited references ↓
- Specify the vertebral level(s) affected by name (e.g., C7, T1) so the cervicothoracic region assignment is unambiguous and defensible on audit.
- Record MRI findings explicitly: vertebral endplate erosion, marrow edema pattern, presence or absence of paraspinal or epidural abscess, and any cord compromise.
- Document elevated inflammatory markers (ESR, CRP) and blood culture results — if an organism is identified, an additional infectious etiology code from A00–B99 is required by ICD-10-CM convention.
- Note whether infection is hematogenous, contiguous spread, or post-procedural; post-procedural vertebral osteomyelitis may require a different code pathway.
- Record prior antibiotic therapy and its duration — payers often require evidence of treatment failure or severity to support surgical intervention claims.
Related CPT procedures
Procedure codes commonly billed with M46.23. Linking the right diagnosis to the right procedure is what establishes medical necessity.
Source · CMS LCDs · AAOS specialty guidance · claims-pattern analysis
Common coding pitfalls
The recurring mistakes coders make with M46.23 and adjacent codes.
Source · Editorial brief grounded in CDC ICD-10-CM tabular guidance, AAOS coding references, and cited references ↓
- Defaulting to M46.22 (cervical) or M46.24 (thoracic) when the provider documents C7–T1 involvement — the cervicothoracic junction belongs to M46.23.
- Omitting an additional code for the causative organism when culture or pathology identifies the specific pathogen, which is required under ICD-10-CM etiology/manifestation conventions.
- Applying a 7th-character extension to M46.23 — this M-code category does not use encounter-type 7th characters; doing so will create an invalid code.
- Confusing osteomyelitis of the vertebra (M46.23) with infection of the intervertebral disc (M46.33, cervicothoracic pyogenic discitis) — these are distinct structures and distinct codes; dual pathology requires both codes.
- Using an unspecified vertebral osteomyelitis code (M46.20) when the region is documented — region specificity is available and required when documented.
Clinical context
Source · Editorial summary grounded in 5 cited references ↓
M46.23 applies when osteomyelitis is documented specifically at the cervicothoracic region — the junction spanning the lower cervical and upper thoracic vertebrae (typically C7–T1). This region designation is the entire basis for selecting this code over adjacent siblings: M46.22 (cervical region) or M46.24 (thoracic region). If the operative or imaging report identifies the affected vertebral levels as spanning or centered at C7–T1, M46.23 is the correct code; if the infection is confined to the mid-cervical or mid-thoracic vertebrae, use the region-specific sibling instead.
Vertebral osteomyelitis at the cervicothoracic junction typically presents with neck and upper back pain, fever, and elevated inflammatory markers (ESR, CRP). MRI is the gold-standard imaging modality, showing endplate erosion, vertebral body marrow signal change, and potential paraspinal or epidural abscess. The causative organism — most commonly Staphylococcus aureus in hematogenous cases — should be captured with an additional code from Chapter 1 (A00–B99) when identified, per ICD-10-CM coding conventions for infectious etiology.
This code sits under category M46 (Other inflammatory spondylopathies) within the Spondylopathies block (M45–M49). It does not carry 7th-character extensions — M-codes in this category are fully specified at 5 characters. For surgical planning involving spinal fusion or debridement at the cervicothoracic level, M46.23 is a supported supporting diagnosis; confirm payer-specific LCD/NCD requirements, as CMS lumbar fusion billing articles (e.g., A56396) list analogous thoracolumbar and lumbar osteomyelitis codes, not cervicothoracic ones, for that procedure.
Sibling codes
Other billable codes under M46.2 (laterality / anatomic variants).
Frequently asked questions
Source · Generated from the editorial pipeline, verified against 5 cited references ↓
01Which vertebral levels define the cervicothoracic region for M46.23?
02Do I need an additional code for the causative organism?
03Can M46.23 and M46.33 be coded together if both the vertebra and the adjacent disc are infected?
04Does M46.23 require a 7th-character extension for initial vs. subsequent encounter?
05Is M46.23 appropriate for post-surgical vertebral infection at the cervicothoracic level?
06What imaging is typically needed to support M46.23 on audit?
07How does M46.23 differ from M46.53 (other infective spondylopathies, cervicothoracic)?
Sources & references
Editorial content was developed using the following public sources. Last verified May 8, 2026.
- 01CDC ICD-10-CM Tabular List 2026 (effective Oct 1, 2025)
- 02icd10data.comhttps://www.icd10data.com/ICD10CM/Codes/M00-M99/M45-M49/M46-/M46.23
- 03aapc.comhttps://www.aapc.com/codes/icd-10-codes/M46.23
- 04cms.govhttps://www.cms.gov/medicare-coverage-database/view/article.aspx?articleid=56396
- 05ftp.cdc.govhttps://ftp.cdc.gov/pub/health_statistics/nchs/publications/ICD10CM/2022/icd10cm-tabular-2022-April-1.pdf
Mira AI Scribe
The Mira AI Scribe captures vertebral level(s) at the cervicothoracic junction (C7–T1), MRI findings (endplate erosion, marrow edema, epidural or paraspinal abscess), inflammatory marker values (ESR, CRP), and any identified organism from blood or tissue cultures. Capturing these specifics prevents region-downcode to M46.20 (unspecified site) and ensures the causative organism is separately coded — both common audit flags for vertebral infection claims.
See how Mira captures M46.23 documentation