ICD-10-CM · Spine

M46.50

Infectious involvement of the spine without a documented or determinable vertebral site — used when the spinal region affected by infection has not been specified in clinical documentation.

Verified May 8, 2026 · 4 sources ↓

Status: Billable
Chapter: 13
Related CPT: 8
Region: Spine

Drawn from CDCICD10DataFindacodeCMS

Documentation tips

What should appear in the chart to support M46.50.

Source · Editorial brief grounded in 4 cited references ↓

Document the specific vertebral region by name (e.g., lumbar, thoracic) as soon as imaging or operative findings confirm it — this allows upgrading to a site-specific M46.5x code.
Record the causative organism or suspected pathogen (e.g., Staphylococcus, Mycobacterium tuberculosis, Brucella) to support additional etiology codes and justify medical necessity.
Note the source and date of imaging (MRI, CT, bone scan) and whether it has been interpreted — an interpreted image on file with no site code is an audit red flag.
If the infection is post-surgical, document the prior procedure, the surgical level, and date of the index surgery to establish context for the infective spondylopathy.
Explicitly state if the spinal site is 'pending further imaging' or 'not yet determined' to justify use of the unspecified code rather than a coder inferring a site.

Related CPT procedures

Procedure codes commonly billed with M46.50. Linking the right diagnosis to the right procedure is what establishes medical necessity.

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

22010 $950.92

Open incision and drainage of a deep subfascial abscess located along the posterior cervical, thoracic, or cervicothoracic spine

22015 $921.86

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

22325 $1,444.25

Open posterior reduction and stabilization of a lumbar vertebral fracture or dislocation, performed through a posterior surgical approach.

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.

20610 $68.81

Aspiration and/or injection of a major joint or bursa (shoulder, hip, knee, or subacromial bursa) performed without ultrasound guidance.

99213 $95.19

Established patient office or outpatient visit requiring 20–29 minutes of total time or low-complexity medical decision-making.

99214 $135.61

Office visit for an established patient requiring moderate-complexity medical decision making (MDM), or 30–39 minutes of total provider time on the date of service.

Common coding pitfalls

The recurring mistakes coders make with M46.50 and adjacent codes.

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

Defaulting to M46.50 when the MRI or operative report already documents the spinal level — assign the site-specific M46.5x code instead; M46.50 is not a safe default.
Confusing M46.50 with M46.4x (discitis, unspecified) — infective spondylopathy involves the vertebral body and surrounding structures, not exclusively the disc space.
Failing to add a causative organism code (e.g., from B90–B94 or A41.x) when the pathogen is documented — M46.50 alone does not convey the infectious etiology.
Using M46.50 for pyogenic vertebral osteomyelitis — that condition codes to M46.2x (osteomyelitis of vertebra), not M46.5x.
Not updating M46.50 to a site-specific code between encounters when imaging results arrive mid-treatment — leaving the unspecified code on recurring claims invites downcoding or denial.

Clinical context

Source · Editorial summary grounded in 4 cited references ↓

M46.50 captures infective spondylopathies that are not pyogenic (vertebral osteomyelitis) and not discitis coded elsewhere, but whose spinal site remains unspecified. Conditions that may fall here include spinal tuberculosis, brucellosis of the spine, or other bacterial/fungal/parasitic spinal infections where the treating provider has not documented which vertebral region is involved. It sits under parent code M46.5, which has site-specific children running from M46.51 (occipito-atlanto-axial) through M46.59 (multiple sites).

Use M46.50 only when the record genuinely lacks site documentation — not as a shortcut when imaging or operative notes identify the affected region. If the cervical, thoracic, lumbar, or sacral level is documented anywhere in the encounter (H&P, MRI report, operative note), assign the corresponding site-specific code instead. Payers and RAC auditors flag M46.50 as a specificity gap when imaging has already been interpreted and filed in the same claim.

For orthopedic practices, M46.50 appears most often in the context of post-surgical spinal infections being worked up before the exact level is confirmed, or in consultation notes where the infectious source is known but the vertebral column distribution is pending advanced imaging. Once imaging results are available, update the code to the appropriate site-specific M46.5x before billing or, at minimum, before the next encounter.

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

M46.54

Other infective spondylopathies, thoracic region

M46.57

Other infective spondylopathies, lumbosacral region

M46.52

Other infective spondylopathies, cervical region

Frequently asked questions

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

01When is M46.50 appropriate versus a site-specific M46.5x code?

Use M46.50 only when no vertebral region has been documented anywhere in the current encounter record. If imaging, operative notes, or the provider's clinical assessment identifies a spinal level or region, assign the corresponding site-specific code (M46.51–M46.59).

02Does M46.50 cover vertebral osteomyelitis?

No. Pyogenic vertebral osteomyelitis codes to M46.2x. M46.50 is for other infective spondylopathies — such as those caused by tuberculosis, brucellosis, or fungal organisms — where the infection involves the spine but does not map to osteomyelitis or discitis.

03Should a causative organism code be added alongside M46.50?

Yes, when the organism is documented. Assign an additional code from the appropriate infectious disease category (e.g., B90.9 for sequelae of tuberculosis, A23.9 for brucellosis) to fully represent the clinical picture and satisfy medical necessity requirements.

04Can M46.50 be used for post-surgical spinal infections?

It can be used in the early workup phase when the site is genuinely unconfirmed, but post-surgical infection typically also requires a complication code (T84.6xxA/D/S or similar) to capture the surgical context. Do not use M46.50 alone if the surgical level is already documented.

05Is M46.50 valid for outpatient claims in FY2026?

Yes, M46.50 is a billable code valid for FY2026 outpatient claims. However, CMS and commercial payers expect site specificity when clinical documentation supports it — sustained use of the unspecified code across multiple encounters for the same patient is an audit trigger.

06What is the difference between M46.50 and M46.40 (discitis, site unspecified)?

M46.40 is restricted to inflammation of the intervertebral disc space. M46.50 covers broader spinal infections involving vertebral bodies and surrounding structures. When the infection has spread beyond the disc to the vertebra or epidural space, M46.50 (or M46.2x for osteomyelitis) is more appropriate than M46.40.

Sources & references

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

Mira AI Scribe

Mira AI Scribe captures the vertebral region from imaging impressions, operative notes, and provider dictation — including MRI level designations (e.g., 'L3–L4 involvement') and organism findings from biopsy or culture. Documenting the specific spinal region at the point of care prevents M46.50 from persisting on the claim when a site-specific M46.5x code is supportable, eliminating a common specificity audit flag.

See how Mira captures M46.50 documentation