Pyogenic bacterial infection of the intervertebral disc localized to the cervicothoracic spinal region, spanning the C7-T1 junction.

Documentation tips

What should appear in the chart to support M46.33.

Source · Editorial brief grounded in 5 cited references ↓

• Explicitly state 'cervicothoracic' or 'C7-T1' in the assessment — 'cervical' alone maps to M46.32 and 'thoracic' alone maps to M46.34.
• Record the causative organism by name and source (blood culture, disc aspirate, biopsy) to support the required B95–B97 secondary code.
• Document MRI or CT findings that confirm disc involvement: T2 signal change, endplate erosion, paravertebral or epidural extension.
• Note prior antibiotic therapy, duration, and response — payers use this to assess medical necessity for surgical debridement or prolonged IV antibiotics.
• If osteomyelitis of the adjacent vertebra is also present, document it separately so M46.23 can be added as a concurrent code.
• Record ESR, CRP, WBC, and procalcitonin values in the clinical note to substantiate severity and support inpatient-level medical necessity if applicable.

Related CPT procedures

Procedure codes commonly billed with M46.33. 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 M46.33 and adjacent codes.

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

• Using parent code M46.3 for billing — it is non-billable; always code to the site-specific 5th character (M46.33 for cervicothoracic).
• Omitting the mandatory B95–B97 organism identification code; the tabular 'Use Additional' instruction at M46.3 makes this a required secondary code, not optional.
• Selecting M46.43 (discitis, unspecified, cervicothoracic) when the infection is confirmed as pyogenic — M46.33 is the correct, more specific code.
• Mapping to M46.32 (cervical region) or M46.34 (thoracic region) when documentation clearly identifies the C7-T1 junction — region precision matters for site-specific coding.
• Confusing M46.53 (other infective spondylopathies, cervicothoracic) with M46.33 — M46.53 is reserved for non-pyogenic infectious agents such as Mycobacterium tuberculosis or Brucella.
• Failing to add M46.23 when imaging or surgical findings show concurrent vertebral osteomyelitis at the same level — disc infection and vertebral osteomyelitis are distinct and separately reportable.

Clinical context

Source · Editorial summary grounded in 5 cited references ↓

Sibling codes

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