M46.58 identifies infectious disease involving the vertebral structures of the sacral and sacrococcygeal region — the lower sacrum through the coccyx — caused by pathogens other than those classified under pyogenic or tuberculous spondylitis codes.

Documentation tips

What should appear in the chart to support M46.58.

Source · Editorial brief grounded in 5 cited references ↓

• Specify anatomical level explicitly: 'sacral,' 'sacrococcygeal,' or 'coccyx' — generic 'low back' won't support M46.58 over a lumbar or lumbosacral code.
• Record the causative organism or pathogen class (bacterial, fungal, brucellar) and reference positive culture, serology, or biopsy results to substantiate the infectious etiology.
• Document imaging findings — MRI signal changes at the sacrum, CT-guided biopsy results, or bone scan uptake — that confirm an infective rather than inflammatory or neoplastic process.
• If conservative treatment with antibiotics preceded surgical intervention, document that failure of non-operative management in the note to support medical necessity for any procedural coding.
• Note any systemic infectious findings (fever, elevated ESR/CRP, positive blood cultures) that corroborate the infectious spondylopathy diagnosis.

Related CPT procedures

Procedure codes commonly billed with M46.58. 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 M46.58 and adjacent codes.

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

• Defaulting to M46.57 (lumbosacral) when the documented site is clearly the sacrum or sacrococcygeal region — the two are distinct anatomical locations with different codes.
• Using M46.58 for sacroiliac joint infections; septic sacroiliitis maps instead to M01.x5x (direct infection of hip/pelvic joints) or relevant infectious arthritis codes, not the spondylopathy block.
• Assigning M46.58 when the infection is pyogenic vertebral osteomyelitis — that presentation belongs in M46.2x, not M46.5x.
• Failing to code also the causative organism (e.g., B01–B99 range) when known — the Tabular List Use Additional Code instruction applies to the M46.5x category.
• Selecting M46.50 (site unspecified) when the provider has documented the sacral level — unspecified codes trigger payer scrutiny and reduce DRG accuracy.

Clinical context

Source · Editorial summary grounded in 5 cited references ↓

Sibling codes

Other billable codes under M46.5 (laterality / anatomic variants).