Bacterial or hematogenous infection of the vertebral bone body confined to the lumbar spinal region (L1–L5), classified under other inflammatory spondylopathies.

Documentation tips

What should appear in the chart to support M46.26.

Source · Editorial brief grounded in 6 cited references ↓

• Specify the lumbar region explicitly (L1–L5) in the assessment or operative report — 'lumbar vertebral osteomyelitis' is the minimum acceptable phrase to support M46.26 over the unspecified M46.20.
• Record the imaging modality and findings that confirm diagnosis: MRI signal changes at vertebral endplates, bone marrow edema, cortical destruction, or contrast enhancement consistent with infection.
• Document the causative organism and source when identified — add a B95–B97 or A18.01 code alongside M46.26 to capture pathogen and drive appropriate CC/MCC capture.
• If an epidural or paraspinal abscess is present, document and code it separately (e.g., G06.1); this frequently elevates the encounter to MCC status.
• Note any prior spinal surgery, IV drug use, recent bacteremia, or immunocompromised state in the history — these are audit-relevant risk factors that support medical necessity for advanced imaging and prolonged antibiotic therapy.
• If disease spans a junction (e.g., L1 and T12), document the primary and secondary levels so the coder can evaluate whether M46.25 (thoracolumbar) or M46.26 (lumbar) better reflects the principal site.

Related CPT procedures

Procedure codes commonly billed with M46.26. 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 M46.26 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 note or MRI report clearly names lumbar vertebrae — always assign the most specific region code supported by documentation.
• Confusing M46.26 (osteomyelitis of lumbar vertebra) with M46.36 (infection of lumbar intervertebral disc) — vertebral body infection and disc space infection are distinct entities with separate codes; discitis alone is M46.36.
• Omitting the causative organism code (B95–B97 series or A18.01 for TB) when culture or pathology results are available — failing to add this secondary code leaves CC/MCC value on the table.
• Using M86.9 (general osteomyelitis, unspecified) when the vertebral location is documented — M46.26 is the site-specific code and should be used instead of the non-specific M86 category for vertebral involvement.
• Assigning M46.26 for lumbosacral or thoracolumbar junction disease without checking adjacent codes M46.25 and M46.27 — the region documented in imaging dictates the correct 6th character.

Clinical context

Source · Editorial summary grounded in 6 cited references ↓

Sibling codes

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