ICD-10-CM · Spine

M46.56

M46.56 classifies infectious conditions of the lumbar vertebrae and surrounding spinal structures that are not captured by more specific infective spondylopathy codes (e.g., pyogenic vertebral osteomyelitis or tuberculous spondylitis), localized to the L1–L5 region.

Verified May 8, 2026 · 4 sources ↓

Status: Billable
Chapter: 13
Related CPT: 10
Region: Spine

Drawn from CDCICD10DataAAPCCMS

Documentation tips

What should appear in the chart to support M46.56.

Source · Editorial brief grounded in 4 cited references ↓

Specify 'lumbar' or the exact vertebral level (e.g., L2-L3) in the diagnosis statement — 'lumbar region' is required to justify M46.56 over M46.50 (site unspecified).
Document the causative organism or at minimum the infection type (bacterial, fungal, brucella) so an additional organism code can be assigned per ICD-10-CM instructional notation.
Record imaging findings (MRI with contrast, CT) that confirm vertebral or paravertebral infectious involvement — end-plate erosion, paraspinal abscess, disc signal change.
Note any prior antibiotic course, blood culture results, or biopsy findings; these support medical necessity and defend against payer audit on infectious spinal diagnoses.
Distinguish between vertebral body infection and intervertebral disc infection in the clinical note — M46.36 may be the more precise code if disc space infection is the primary finding.

Related CPT procedures

Procedure codes commonly billed with M46.56. 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.

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.

22633 $1,700.11

Single-level lumbar arthrodesis combining posterior or posterolateral technique with posterior interbody technique, including laminectomy and/or discectomy sufficient to prepare the interspace — performed as one surgical session at one lumbar interspace.

22840 $668.35

Posterior non-segmental instrumentation placed during spinal surgery, using rods, hooks, or wires that span multiple vertebral levels without anchoring at each intervening segment.

22842 $680.04

Posterior segmental spinal instrumentation spanning 3 to 6 vertebral segments, reported as an add-on to the primary spinal procedure code.

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.

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.

72158 $318.31

MRI of the lumbar spinal canal and its contents performed first without contrast, then repeated after contrast administration for enhanced visualization.

77080 View procedure details

Common coding pitfalls

The recurring mistakes coders make with M46.56 and adjacent codes.

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

Defaulting to M46.56 when the infection is clearly pyogenic vertebral osteomyelitis (M46.26) or intervertebral disc infection (M46.36) — review the full M46 subcategory before assigning.
Assigning M46.50 (site unspecified) when the provider has documented lumbar involvement — missing the region specificity at the sixth character is a specificity downcode that can trigger claim review.
Omitting the causative organism code (e.g., A23.9 for brucellosis, B49 for unspecified mycosis) when the etiology is documented — category M46.5 carries a 'Use Additional Code' instruction for the infectious agent.
Coding M46.56 for lumbosacral involvement without considering M46.57 (lumbosacral region) — if the infection bridges the L5-S1 junction, lumbosacral may be the anatomically correct region code.

Clinical context

Source · Editorial summary grounded in 4 cited references ↓

Use M46.56 when the documented diagnosis is an infective spondylopathy of the lumbar spine and the causative organism or condition does not map to a more specific code under M46 or related categories. Common clinical scenarios include bacterial discitis, fungal spondylitis, or brucella-related vertebral infection of the lumbar spine when the provider documents infection of the lumbar vertebral column without further specificity that would redirect to osteomyelitis (M46.2x) or intervertebral disc infection (M46.3x).

M46.56 sits under parent code M46.5 (Other infective spondylopathies), which is region-specific. Before landing here, confirm the infection is lumbar — codes exist for cervical (M46.52), thoracic (M46.54), and other regions. If the record documents both lumbar and another level, assign codes for each affected region. Do not use M46.56 for discogenic infections clearly classified as disc inflammation; check whether M46.36 (Infection of intervertebral disc, lumbar region) is more appropriate.

Sequencing matters: ICD-10-CM conventions require that when an underlying infectious etiology is documented, the causative organism code (e.g., B. melitensis, Staphylococcus aureus) be assigned as an additional code per 'Use Additional Code' instructions at the category level. Failure to assign the organism code is a common audit flag in infectious musculoskeletal cases.

Sibling codes

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

M46.53

Other infective spondylopathies, cervicothoracic region

M46.51

Oth infective spondylopathies, occipito-atlanto-axial region

M46.55

Other infective spondylopathies, thoracolumbar region

M46.59

Other infective spondylopathies, multiple sites in spine

M46.58

Oth infective spondylopathies, sacr/sacrocygl region

M46.50

Other infective spondylopathies, site unspecified

M46.54

Other infective spondylopathies, thoracic region

M46.57

Other infective spondylopathies, lumbosacral region

Frequently asked questions

Source · Generated from the editorial pipeline, verified against 4 cited references ↓

01What is the difference between M46.56 and M46.36?

M46.36 codes infection of the intervertebral disc specifically in the lumbar region. M46.56 covers other infective spondylopathies of the lumbar region — meaning vertebral body or broader spinal infection not classified as disc-space infection. If the MRI and clinical note clearly identify the disc as the primary infected structure, M46.36 is more precise.

02Do I need to add an organism code with M46.56?

Yes. ICD-10-CM instructs coders to use an additional code to identify the infectious agent when documented. Assign the appropriate organism code (e.g., A23.x for brucellosis, B38.x for coccidioidomycosis) as a secondary code. Omitting it is an audit flag.

03Can M46.56 be used for lumbar discitis?

Not if discitis is the primary diagnosis. Infective discitis of the lumbar spine maps to M46.36 (Infection of intervertebral disc, lumbar region). M46.56 is appropriate when the spondylopathy involves the vertebral body or broader structures and is not specifically disc infection.

04What if the infection spans lumbar and lumbosacral levels?

If the infection involves L5-S1 or the lumbosacral junction, consider M46.57 (Other infective spondylopathies, lumbosacral region). If disease spans both lumbar and lumbosacral regions, assign codes for each affected region per ICD-10-CM multi-level spine coding conventions.

05Is M46.56 appropriate for tuberculosis of the lumbar spine?

No. Tuberculous spondylitis has its own code: A18.01 (Tuberculosis of spine). M46.56 is reserved for infective spondylopathies not captured by more specific infectious spine codes. When TB is documented, sequence A18.01 first.

06Does M46.56 require a 7th character extension?

No. M46.56 is a complete six-character code and does not use 7th-character extensions. The 7th-character A/D/S convention applies to injury codes in Chapter 19 (S- and T-codes), not to musculoskeletal disease codes in Chapter 13.

07What imaging supports M46.56 for prior authorization or audit purposes?

MRI of the lumbar spine with and without contrast is the standard modality — document end-plate erosion, disc signal changes, paraspinal or epidural abscess formation, and vertebral body marrow edema. CT-guided biopsy culture results further substantiate the infectious etiology.

Sources & references

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

01CDC ICD-10-CM Tabular List 2026 (effective Oct 1, 2025)
02
icd10data.com
https://www.icd10data.com/ICD10CM/Codes/M00-M99/M45-M49/M46-/M46.56
03
aapc.com
https://www.aapc.com/codes/icd-10-codes/M46.56
04
cms.gov
https://www.cms.gov/files/document/fy-2025-icd-10-cm-coding-guidelines.pdf

Mira AI Scribe

Mira's AI scribe captures lumbar-level documentation from the encounter — vertebral levels named, infection type characterized (bacterial, fungal, brucella), and imaging findings such as MRI end-plate erosion or paraspinal abscess — and tags the causative organism from labs or culture results for dual-code assignment. This prevents region-unspecified fallback to M46.50 and eliminates the audit risk of a standalone infective spondylopathy code missing its required organism companion.

See how Mira captures M46.56 documentation