ICD-10-CM · Spine

M46.20

Vertebral osteomyelitis with no spinal region documented — use only when the treating clinician has not specified which section of the spine is affected.

Verified May 8, 2026 · 6 sources ↓

Status: Billable
Chapter: 13
Related CPT: 15
Region: Spine

Drawn from CDCICD10DataCMSNIHAAPC

Documentation tips

What should appear in the chart to support M46.20.

Source · Editorial brief grounded in 6 cited references ↓

Name the spinal region affected (cervical, thoracic, lumbar, etc.) in every note — this single detail moves the code from unspecified M46.20 to a site-specific M46.21–M46.28.
Record whether the infection is acute or chronic; both map to M46.20 when site is unspecified, but acuity drives clinical management documentation and supports medical necessity.
Document the causative organism if identified (blood culture, biopsy, or intraoperative culture) and add a secondary B95–B97 pathogen code.
Specify on imaging reports whether the disc space is involved — if pyogenic discitis is also present, M46.30–M46.38 should be coded concurrently.
Note any history of prior spinal surgery, IV drug use, or immunocompromise; these risk factors support medical necessity and may affect DRG severity.

Related CPT procedures

Procedure codes commonly billed with M46.20. Linking the right diagnosis to the right procedure is what establishes medical necessity.

Source · CMS LCDs · AAOS specialty guidance · claims-pattern analysis

22558 $1,423.88

Anterior interbody arthrodesis of the lumbar spine using an anterior or anterolateral approach, including the minimal discectomy required to prepare the interspace for fusion.

22600 $1,282.93

Posterior or posterolateral cervical spinal fusion at a single interspace below C2, performed through a posterior approach to achieve bony arthrodesis.

22612 $1,467.64

Posterior or posterolateral lumbar arthrodesis of a single interspace, performed via a posterior approach with bone graft and typically pedicle screw fixation to achieve vertebral segment fusion.

22630 $1,510.72

Posterior interbody arthrodesis of a single lumbar interspace, including laminectomy and/or discectomy performed to prepare the interspace for fusion rather than for decompression.

22800 $1,312.99

Posterior spinal arthrodesis for deformity correction spanning up to 6 vertebral segments, with or without application of a body cast.

63030 $898.15

Single-interspace lumbar laminotomy with nerve root decompression, including partial facetectomy, foraminotomy, and/or herniated disc excision performed via open surgical technique.

63047 $1,065.49

Lumbar laminectomy at a single vertebral segment that also includes facetectomy and foraminotomy for decompression of the spinal cord, cauda equina, and/or nerve roots — unilateral or bilateral.

63056 $1,404.84

Lumbar spinal cord and nerve root decompression via transpedicular approach, single segment, including transfacet or lateral extraforaminal variants for far lateral disc herniations.

72100 $40.42

Radiologic examination of the lumbosacral spine capturing two or three views, used to evaluate the lumbar vertebrae and sacrum for injury, degeneration, or structural abnormality.

72148 $191.72

Non-contrast MRI of the lumbar spine used to evaluate disc pathology, spinal stenosis, nerve root compression, and other structural abnormalities without administration of contrast material.

20245 $303.28

Surgical removal of a bone tissue sample from a deep anatomical site — such as the humeral shaft, ischium, or femoral shaft — through an open incision for pathological analysis.

20250 $387.45

Open surgical biopsy of a thoracic vertebral body, requiring an incision to directly access and remove bone tissue for pathological analysis.

20251 $421.19

Open surgical biopsy of the vertebral body, performed at the lumbar or cervical level, to obtain tissue for pathologic diagnosis.

72157 View procedure details

72200 View procedure details

Common coding pitfalls

The recurring mistakes coders make with M46.20 and adjacent codes.

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

Defaulting to M86.9 (Osteomyelitis, unspecified) instead of M46.20 for vertebral infections — the ICD-10-CM index directs vertebral osteomyelitis to M46.2x, not M86.
Using M46.20 when imaging or the operative note actually identifies the spinal level — if the level is documented, code the site-specific subcategory (M46.21–M46.28).
Omitting a secondary code for the causative organism when culture or sensitivity results are available in the record.
Failing to code concurrent pyogenic intervertebral disc infection (M46.30–M46.38) separately when both vertebral body and disc space are infected.
Confusing M46.20 with M46.30 (infection of intervertebral disc, site unspecified) — these are distinct anatomic structures and separate codes, even when they co-occur.

Clinical context

Source · Editorial summary grounded in 6 cited references ↓

M46.20 captures bone infection of a vertebra when the operative report, office note, or imaging read does not identify the affected spinal region. The M46.2x family runs from occipito-atlanto-axial (M46.21) through sacral/sacrococcygeal (M46.28), so M46.20 should be a last resort, not a default. If the chart documents even a general region — lumbar, thoracic, cervical — code to that specificity.

Vertebral osteomyelitis is classified under Other Inflammatory Spondylopathies (M46), not under the general osteomyelitis category M86. This distinction matters for DRG assignment: M46.20 maps to MS-DRG 539/540/541 (Osteomyelitis with/without MCC/CC) and to MS-DRG 456/457/458 (Spinal fusion with infection) when a fusion procedure is also reported. Coding to M86.x instead of M46.20 for vertebral infection is a common and auditable error.

Approximate synonyms accepted under this code include acute osteomyelitis of vertebra, chronic osteomyelitis of vertebra, and osteomyelitis of the spine (unspecified). When the causative organism is known, add a secondary code from B95–B97 to identify the pathogen. Also consider whether a concurrent pyogenic intervertebral disc infection (M46.30) should be coded in addition.

Sibling codes

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

M46.27

Osteomyelitis of vertebra, lumbosacral region

M46.23

Osteomyelitis of vertebra, cervicothoracic region

M46.25

Osteomyelitis of vertebra, thoracolumbar region

M46.21

Osteomyelitis of vertebra, occipito-atlanto-axial region

M46.28

Osteomyelitis of vertebra, sacral and sacrococcygeal region

M46.26

Osteomyelitis of vertebra, lumbar region

M46.24

Osteomyelitis of vertebra, thoracic region

M46.22

Osteomyelitis of vertebra, cervical region

Frequently asked questions

Source · Generated from the editorial pipeline, verified against 6 cited references ↓

01When is M46.20 appropriate versus a site-specific M46.2x code?

Use M46.20 only when no spinal region is documented anywhere in the encounter record. If the clinician, radiologist, or operative note names a region — even broadly (e.g., 'lumbar spine') — code to the corresponding site-specific code (e.g., M46.26 for lumbar).

02Should I use M46.20 or M86.x for vertebral osteomyelitis?

Use M46.20 (or the appropriate site-specific M46.2x). The ICD-10-CM alphabetic index routes vertebral osteomyelitis to M46.2, not M86. Using M86.x for a vertebral infection is a coding error and an audit risk.

03Does M46.20 cover both acute and chronic vertebral osteomyelitis?

Yes. Both acute and chronic osteomyelitis of the vertebra with unspecified site map to M46.20. Acuity is not distinguished at the code level within M46.2x, but it should still be documented for clinical and medical necessity purposes.

04Which MS-DRGs does M46.20 map to?

M46.20 maps to MS-DRG 539/540/541 (Osteomyelitis with MCC, with CC, without CC/MCC) and to MS-DRG 456/457/458 (Spinal fusion with infection) when a concurrent spinal fusion CPT is reported, per CMS MS-DRG v43.0.

05Should I add a secondary code for the infecting organism?

Yes, when culture or sensitivity results identify the pathogen. Add a code from B95 (Streptococcus/Staphylococcus), B96 (other bacterial agents), or B97 (viral agents) as a secondary diagnosis. This improves specificity and can affect case mix index.

06If both the vertebral body and the disc are infected, do I code both M46.20 and M46.30?

Yes. Vertebral osteomyelitis (M46.2x) and pyogenic intervertebral disc infection (M46.3x) are separate conditions and separate codes. When both structures are involved and documented, report both codes. Use site-specific subcategories if the region is documented.

07Is M46.20 valid for inpatient and outpatient encounters?

M46.20 is a billable code valid for both settings. However, payer and facility coding guidelines may flag unspecified codes for additional documentation requests, particularly on inpatient claims where DRG optimization depends on specificity.

Sources & references

Editorial content was developed using the following public sources. Last verified May 8, 2026.

Mira AI Scribe

Mira AI Scribe captures the spinal region named by the clinician (cervical, thoracic, lumbar, lumbosacral, etc.), acuity (acute vs. chronic), organism if cultured, disc involvement, and any imaging findings such as MRI signal changes or endplate destruction. Locking in the spinal region at encounter prevents a site-unspecified fallback to M46.20 and avoids downstream DRG downcoding or payer queries.

See how Mira captures M46.20 documentation