Pyogenic (bacterial) infection of one or more intervertebral discs in the lumbar spine region, classified under other inflammatory spondylopathies.

Documentation tips

What should appear in the chart to support M46.36.

Source · Editorial brief grounded in 5 cited references ↓

• Specify 'lumbar region' by name and, where possible, the level(s) affected (e.g., L3–L4, L4–L5) to support medical necessity and site specificity.
• Record MRI findings explicitly: T2 hyperintensity in the disc, endplate erosion, and any adjacent vertebral or paraspinal involvement.
• Document inflammatory markers at the time of diagnosis — ESR and CRP values — to substantiate the infectious etiology and severity.
• Identify the causative organism and assign the appropriate B95–B97 code; if cultures are pending, note this in the record and update coding when results return.
• Distinguish whether infection is limited to the disc (M46.36) or has extended to the vertebral body (add M46.26) or formed an abscess (reassess for spondylitis codes), and document accordingly.
• For inpatient cases, the MS-DRG assignment (539–541 Osteomyelitis; 456–458 Spinal Fusion with infection) is driven by MCC/CC status — document comorbidities that qualify as MCC or CC to ensure accurate DRG weight.

Related CPT procedures

Procedure codes commonly billed with M46.36. 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 M46.36 and adjacent codes.

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

• Assigning M46.36 without the required additional B95–B97 organism code violates the tabular 'Use additional code' instruction and invites a claim edit.
• Using M54.5 (low back pain) or M46.46 (discitis, unspecified, lumbar region) when pyogenic infection is confirmed — M46.36 is the more specific, higher-acuity code and must be used when bacterial etiology is documented.
• Confusing lumbar (M46.36) with lumbosacral (M46.37) — if the infected disc is at L5–S1, code M46.37, not M46.36.
• Failing to add M46.26 when imaging also shows lumbar vertebral osteomyelitis — disc infection and vertebral osteomyelitis are coded separately and both should be reported.
• Coding M46.36 for tuberculous or fungal discitis — those infections are classified in M49.0 (spondylopathy in infectious and parasitic diseases) or other category codes; M46.3x is pyogenic (bacterial) only.

Clinical context

Source · Editorial summary grounded in 5 cited references ↓

Sibling codes

Other billable codes under M46.3 (laterality / anatomic variants).