ICD-10-CM · Spine

M46.25

Infectious inflammation of vertebral bone tissue specifically involving the thoracolumbar junction (T12-L1 region), classified under other inflammatory spondylopathies.

Verified May 8, 2026 · 5 sources ↓

Status: Billable
Chapter: 13
Related CPT: 10
Region: Spine

Drawn from CDCICD10DataAAPCFindacodeCMS

Documentation tips

What should appear in the chart to support M46.25.

Source · Editorial brief grounded in 5 cited references ↓

Specify the vertebral level(s) explicitly — T12, L1, or T12-L1 junction — so the thoracolumbar region designation is unambiguous in the record.
Document the causative organism when identified (blood culture, biopsy, or intraoperative specimen) and assign the appropriate B95–B97 or A-category code alongside M46.25.
Record the infection pathway: hematogenous, contiguous spread, or postoperative — this supports medical necessity for advanced imaging and surgical intervention.
If concurrent disc space infection is confirmed, document discitis separately to justify adding M46.35 as a secondary code.
Note imaging findings (MRI signal changes, endplate erosion, paraspinal abscess) and, if applicable, biopsy pathology confirming osteomyelitis — this defends the specificity of M46.25 under audit.

Related CPT procedures

Procedure codes commonly billed with M46.25. Linking the right diagnosis to the right procedure is what establishes medical necessity.

Source · CMS LCDs · AAOS specialty guidance · claims-pattern analysis

22532 $1,732.17

Spinal fusion at a single thoracic vertebral segment using the lateral extracavitary approach, which provides a wide posterolateral corridor to the anterior and middle columns without entering the thoracic cavity. Includes minimal discectomy to prepare the interspace for fusion.

22533 $1,547.80

Spinal fusion of a lumbar vertebral segment performed through a lateral extracavitary approach, including minimal discectomy to prepare the interspace (not performed solely for decompression).

22558 $1,423.88

Anterior interbody arthrodesis of the lumbar spine using an anterior or anterolateral approach, including the minimal discectomy required to prepare the interspace for fusion.

22630 $1,510.72

Posterior interbody arthrodesis of a single lumbar interspace, including laminectomy and/or discectomy performed to prepare the interspace for fusion rather than for decompression.

22633 $1,700.11

Single-level lumbar arthrodesis combining posterior or posterolateral technique with posterior interbody technique, including laminectomy and/or discectomy sufficient to prepare the interspace — performed as one surgical session at one lumbar interspace.

63047 $1,065.49

Lumbar laminectomy at a single vertebral segment that also includes facetectomy and foraminotomy for decompression of the spinal cord, cauda equina, and/or nerve roots — unilateral or bilateral.

63048 $187.38

Add-on code for laminectomy, facetectomy, and foraminotomy at each additional cervical, thoracic, or lumbar vertebral segment beyond the primary segment.

72148 $191.72

Non-contrast MRI of the lumbar spine used to evaluate disc pathology, spinal stenosis, nerve root compression, and other structural abnormalities without administration of contrast material.

72158 $318.31

MRI of the lumbar spinal canal and its contents performed first without contrast, then repeated after contrast administration for enhanced visualization.

20251 $421.19

Open surgical biopsy of the vertebral body, performed at the lumbar or cervical level, to obtain tissue for pathologic diagnosis.

Common coding pitfalls

The recurring mistakes coders make with M46.25 and adjacent codes.

Source · Editorial brief grounded in CDC ICD-10-CM tabular guidance, AAOS coding references, and cited references ↓

Defaulting to M46.20 (site unspecified) when the operative or MRI report clearly documents T12-L1 involvement — always assign M46.25 when the thoracolumbar region is documented.
Using M46.24 (thoracic) or M46.26 (lumbar) when the infection spans the T12-L1 junction — the thoracolumbar region code (M46.25) is the correct choice for that transitional zone.
Failing to add a secondary code for the infectious organism when culture results are documented, which leaves payer-reportable data on the table and can trigger a specificity query.
Confusing M46.25 with M46.55 (Other infective spondylopathies, thoracolumbar region) — M46.25 is specific to vertebral bone infection; M46.55 covers other infective spondylopathies not classified to osteomyelitis.
Routing tuberculous vertebral infection to M46.25 — A18.01 (Tuberculosis of spine) is the correct code; M46.25 does not cover TB spondylitis.

Clinical context

Source · Editorial summary grounded in 5 cited references ↓

M46.25 applies when osteomyelitis is documented at the thoracolumbar junction — the transitional zone between T12 and L1. This region is a biomechanically distinct segment, and infections here can arise hematogenously, by direct extension from adjacent discitis, or postoperatively. The code sits under parent M46.2 (Osteomyelitis of vertebra), and the fifth character '5' locks in the thoracolumbar region specifically. Do not use M46.24 (thoracic) or M46.26 (lumbar) if the documented level straddles T12-L1.

If intervertebral disc infection accompanies the vertebral osteomyelitis, add M46.35 (Infection of intervertebral disc, thoracolumbar region) as a secondary code — these are distinct structures and distinct codes. When the causative organism is known, assign an additional code for the infectious agent (e.g., a B95–B97 code for bacterial or viral etiology). Tuberculosis of the spine is excluded from M46.25; that routes to A18.01.

M46.25 is a fully billable, specific ICD-10-CM code requiring no further character extension. It is valid for outpatient, inpatient, and surgical facility claims. In the orthopedic context, you will see it paired with spinal decompression, fusion, or biopsy procedures when the infection necessitates surgical intervention.

Sibling codes

Other billable codes under M46.2 (laterality / anatomic variants).

M46.27

Osteomyelitis of vertebra, lumbosacral region

M46.23

Osteomyelitis of vertebra, cervicothoracic region

M46.21

Osteomyelitis of vertebra, occipito-atlanto-axial region

M46.28

Osteomyelitis of vertebra, sacral and sacrococcygeal region

M46.26

Osteomyelitis of vertebra, lumbar region

M46.20

Osteomyelitis of vertebra, site unspecified

M46.24

Osteomyelitis of vertebra, thoracic region

M46.22

Osteomyelitis of vertebra, cervical region

Frequently asked questions

Source · Generated from the editorial pipeline, verified against 5 cited references ↓

01What exactly is the thoracolumbar region for ICD-10-CM coding purposes?

The thoracolumbar region refers to the T12-L1 junction — the transitional zone between the thoracic and lumbar spine. Use M46.25 when documentation or imaging targets that transitional segment. If the infection is clearly confined to the mid-thoracic levels, use M46.24; if clearly lumbar (L2 and below), use M46.26.

02Does M46.25 require a 7th character extension?

No. M46.25 is a 5-character billable code under Chapter 13 (M-codes). Seventh-character extensions (A/D/S) apply to injury S-codes, not to musculoskeletal disease M-codes. Submit M46.25 as-is.

03Should I also code the disc space infection if MRI shows both vertebral osteomyelitis and discitis at the same level?

Yes. Vertebral osteomyelitis (M46.25) and pyogenic disc infection (M46.35) are coded separately when both are documented. They represent distinct anatomic structures with distinct ICD-10-CM codes — assign both.

04Is M46.25 appropriate for tuberculous spondylitis at the thoracolumbar junction?

No. Tuberculosis of the spine routes to A18.01 regardless of spinal level. M46.25 covers non-tuberculous bacterial (or other) osteomyelitis. Using M46.25 for TB will mismatch with payer and public health reporting expectations.

05What secondary codes should accompany M46.25 when the organism is known?

Assign a B95–B97 code to identify the causative organism — for example, B95.61 (Methicillin-susceptible Staphylococcus aureus) or B96.20 (Unspecified Escherichia coli). If the infection is fungal or parasitic, use the appropriate B-category code. ICD-10-CM instructs coders to add an additional code for the infectious agent when known.

06Can M46.25 be the principal diagnosis for a spinal fusion procedure performed to treat the infection?

Yes, when vertebral osteomyelitis is the condition chiefly responsible for the admission and the fusion is performed to stabilize the infected segment, M46.25 can serve as the principal diagnosis. Confirm with your facility's CDI team for inpatient sequencing if multiple complicating conditions exist.

07How does M46.25 differ from M46.55?

M46.25 is specific to osteomyelitis of the vertebral bone at the thoracolumbar region. M46.55 covers other infective spondylopathies at the same region that don't classify as osteomyelitis — for example, certain non-pyogenic or non-bone-specific spinal infections. Choose based on what the clinician documents: confirmed bone infection maps to M46.25.

Sources & references

Editorial content was developed using the following public sources. Last verified May 8, 2026.

01CDC ICD-10-CM Tabular List 2026 (FY2026, effective Oct 1 2025)
02
icd10data.com
https://www.icd10data.com/ICD10CM/Codes/M00-M99/M45-M49/M46-/M46.25
03
aapc.com
https://www.aapc.com/codes/icd-10-codes/M46.25
04
findacode.com
https://www.findacode.com/icd-10-cm/m46.25-osteomyelitis-vertebra-thoracolumbar-region-icd10cm-code.html
05
cms.gov
https://www.cms.gov/medicare-coverage-database/view/article.aspx?articleid=57792&ver=11&

Mira AI Scribe

Mira's AI scribe captures the vertebral level (T12, L1, or T12-L1 junction), MRI or CT findings confirming endplate destruction or bone marrow edema consistent with osteomyelitis, organism identification from culture or biopsy, and any concurrent disc space involvement. This prevents a fallback to M46.20 (unspecified site), protects against a specificity audit flag, and ensures secondary organism codes are queued when culture data is available.

See how Mira captures M46.25 documentation