ICD-10-CM · Spine

M46.57

Infectious inflammation of the spinal vertebrae and associated structures localized to the lumbosacral junction (L5-S1 region), caused by organisms other than those classified under tuberculosis or other specific infective spondylopathies.

Verified May 8, 2026 · 5 sources ↓

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

Drawn from CDCicd10data.com M46.57CMS

Documentation tips

What should appear in the chart to support M46.57.

Source · Editorial brief grounded in 5 cited references ↓

Specify the anatomical level as lumbosacral or L5-S1 — generic 'lumbar' documentation defaults to M46.56, not M46.57.
Record the identified or suspected causative organism explicitly so you can assign the paired B95–B97 organism code required by the Tabular List.
Document whether the infection is hematogenous, post-procedural, or contiguous-spread origin — this affects additional code selection and audit defensibility.
Include MRI or CT findings (endplate erosion, disc space narrowing, paraspinal/epidural phlegmon) to support medical necessity for imaging CPT codes and inpatient DRG assignment.
If IV antibiotics, surgical debridement, or spinal fusion is planned or performed, document that decision and tie it explicitly to the infective diagnosis at this spinal level.

Related CPT procedures

Procedure codes commonly billed with M46.57. Linking the right diagnosis to the right procedure is what establishes medical necessity.

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

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.

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.

22800 $1,312.99

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

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.

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.

20606 $94.19

Aspiration and/or injection of an intermediate joint or bursa — such as the wrist, elbow, ankle, acromioclavicular, temporomandibular, or olecranon bursa — performed with real-time ultrasound guidance and permanent image recording and reporting.

22015 $921.86

Open incision and drainage of a deep subfascial abscess along the posterior lumbar, sacral, or lumbosacral spine.

Common coding pitfalls

The recurring mistakes coders make with M46.57 and adjacent codes.

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

Coding M46.56 (lumbar region) when the provider clearly documents lumbosacral or L5-S1 involvement — these are distinct 7th-character site values and the more specific code should always be used when documented.
Omitting the causative organism code (B95–B97) — the Tabular List instructs 'Use additional code to identify infectious agent,' and skipping it is an audit risk and a data quality failure.
Confusing M46.57 with M46.47 (discitis, lumbosacral) — if the infection is confined to the disc space and documented as discitis, M46.47 is the correct parent subcategory, not M46.5x.
Using M46.57 for tuberculous spondylitis at the lumbosacral level — TB spondylitis routes to M49.07 (spondylopathy in tuberculosis, lumbosacral region), not M46.57.
Defaulting to M46.50 (site unspecified) when the operative or imaging report clearly identifies the lumbosacral junction — query the provider before accepting the unspecified code.

Clinical context

Source · Editorial summary grounded in 5 cited references ↓

M46.57 captures infective spondylopathies at the lumbosacral region (L5-S1) that are not attributable to tuberculosis (which routes to M49.0x) or to discitis classified elsewhere. Common causative organisms include Staphylococcus aureus, gram-negative bacilli, and Brucella species following hematogenous seeding, direct inoculation, or contiguous spread from adjacent tissue infection such as psoas abscess or post-procedural contamination. Use M46.57 when the provider documents infectious or infective spondylitis, spondylodiscitis, or vertebral osteomyelitis specifically involving the lumbosacral level and the causative organism falls outside the more specific M46.5x exclusions.

Pair M46.57 with an additional code to identify the causative organism (B95–B97) per the Tabular List 'Use additional code' instruction. If the infection is post-procedural in origin, a complication code from the T8x range may also be required. This code maps to MS-DRG v43.0 groups 456–458 (spinal fusion with infection) when combined with a spinal fusion procedure, or to DRGs 551–552 (medical back problems) in non-operative admissions — both groupings carry significant weight, making specificity essential for appropriate reimbursement.

Do not use M46.57 for noninfective inflammatory spondylopathies (ankylosing spondylitis, psoriatic spondylitis) or for degenerative disc disease, both of which have separate code families. If the lumbosacral level is not definitively documented, fall back to M46.50 (site unspecified) rather than assuming laterality or region.

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

M46.52

Other infective spondylopathies, cervical region

Frequently asked questions

Source · Generated from the editorial pipeline, verified against 5 cited references ↓

01What is the difference between M46.57 and M46.47?

M46.47 is discitis at the lumbosacral region — infection confined to the intervertebral disc space. M46.57 is a broader infective spondylopathy at the same level, encompassing vertebral body and bony involvement beyond isolated discitis. Use whichever matches the provider's documented clinical characterization.

02Do I need to add a separate organism code with M46.57?

Yes. The ICD-10-CM Tabular List includes a 'Use additional code (B95–B97)' instruction for M46.5x codes. Always append the organism code when the pathogen is identified — for example, B95.61 for MRSA or B96.20 for unspecified E. coli.

03Can M46.57 be used for post-surgical spinal infections at the lumbosacral level?

It can be used as a secondary or additional diagnosis, but a post-procedural complication code from T84.x or T81.4x may be required as the principal or first-listed code depending on the clinical scenario. Follow ICD-10-CM guidelines on sequencing complications of care.

04What MS-DRGs does M46.57 map to?

When paired with a spinal fusion procedure, M46.57 groups to DRGs 456, 457, or 458 (spinal fusion with infection, MCC/CC/no CC). Without a fusion procedure, it groups to DRGs 551 or 552 (medical back problems with/without MCC). The infection designation carries significant weight in both groupings.

05What imaging or lab documentation strengthens M46.57 coding?

MRI findings of T2 hyperintensity in the disc and adjacent endplates, gadolinium enhancement of paraspinal or epidural tissue, and elevated ESR/CRP or positive blood/tissue cultures all support the diagnosis. Document these findings explicitly in the assessment to anchor the code to objective clinical data.

06When should I use M46.50 instead of M46.57?

Use M46.50 (site unspecified) only when the provider's documentation does not identify a specific spinal region. If imaging, operative notes, or the clinical note identifies the lumbosacral junction or L5-S1 level, M46.57 is required — do not default to unspecified when the location is knowable.

07Is M46.57 valid for outpatient and inpatient claims?

Yes. M46.57 is a fully billable, specific ICD-10-CM code valid for both outpatient and inpatient claims effective October 1, 2025 (FY2026 code set). It has been billable without change since its introduction in FY2016.

Sources & references

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

01CDC ICD-10-CM Tabular List 2026 — https://icd10cmtool.cdc.gov/
02icd10data.com M46.57 — https://www.icd10data.com/ICD10CM/Codes/M00-M99/M45-M49/M46-/M46.57
03CMS ICD-10 Code Lists — https://www.cms.gov/medicare/coordination-benefits-recovery/overview/icd-code-lists
04CMS ICD-10-CM FY2025 Coding Guidelines — https://www.cms.gov/files/document/fy-2025-icd-10-cm-coding-guidelines.pdf
05CMS MS-DRG v43.0 Grouper — referenced via icd10data.com DRG mapping for M46.57

Mira AI Scribe

Mira AI Scribe captures the documented spinal level (lumbosacral/L5-S1), identified or suspected organism, infection source (hematogenous, post-procedural, contiguous), relevant MRI/CT findings (endplate erosion, disc signal change, paraspinal abscess), and any prior antibiotic or surgical treatment. This prevents site-level downcoding to M46.50 and ensures the required organism code pairing is flagged at the point of documentation rather than discovered at claim review.

See how Mira captures M46.57 documentation