Bacterial or other microbial infection involving the osseous structures of the sacral vertebrae and/or the sacrococcygeal junction, classified under other inflammatory spondylopathies.

Documentation tips

What should appear in the chart to support M46.28.

Source · Editorial brief grounded in 5 cited references ↓

• Specify 'sacral' or 'sacrococcygeal' by name in the diagnosis statement — do not rely on imaging report language alone to establish site.
• Document whether the osteomyelitis is acute, subacute, or chronic; this affects clinical management decisions and supports medical necessity for advanced imaging or prolonged antibiotic therapy.
• Record the causative organism (e.g., Staphylococcus aureus, gram-negative rod) and note blood culture or bone biopsy results — an additional B95–B96 code may be required to capture the organism.
• If a pressure ulcer, diabetic foot, or surgical site infection is the documented source, state this explicitly in the note to support correct sequencing of the underlying condition as the principal diagnosis.
• Include MRI or nuclear medicine scan findings (e.g., bone marrow edema, cortical destruction, tracer uptake) that confirm vertebral involvement at the sacral level.

Related CPT procedures

Procedure codes commonly billed with M46.28. 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 M46.28 and adjacent codes.

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

• Defaulting to M46.27 (lumbosacral region) when imaging or the operative note clearly localizes infection to the sacrum — always match the documented level, not the nearest familiar code.
• Using M86.08x or another M86 code for sacral vertebral osteomyelitis: M86 covers non-vertebral bones; vertebral osteomyelitis belongs exclusively in M46.2x.
• Omitting the causative-organism code (B95–B96) when the pathogen is documented — payers and quality programs increasingly expect this pairing.
• Incorrect sequencing when diabetes or a pressure ulcer is the underlying cause — placing M46.28 first instead of the driving condition can shift the MS-DRG and trigger a medical necessity audit.
• Confusing M46.28 with M46.38 (infection of intervertebral disc, sacral and sacrococcygeal region) — if both the vertebral body and the disc are infected, both codes should be assigned.

Clinical context

Source · Editorial summary grounded in 5 cited references ↓

Sibling codes

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