ICD-10-CM · Spine

M54.42

M54.42 identifies low back pain (lumbago) occurring together with left-sided sciatic nerve pain — radiating down the left leg along the sciatic nerve distribution — without an identified intervertebral disc disorder as the cause.

Verified May 8, 2026 · 5 sources ↓

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

Drawn from CDCICD10DataAAPCCMS

Documentation tips

What should appear in the chart to support M54.42.

Source · Editorial brief grounded in 5 cited references ↓

Explicitly document 'left side' or 'left-sided' in the assessment — laterality is required to use M54.42 over the unspecified M54.40.
Record straight leg raise (SLR) test results, including the affected side; a positive left SLR supports left-sided sciatic nerve root irritation.
Note whether imaging (MRI, X-ray) was obtained and what it showed — if a disc herniation or degeneration is identified as the cause, the code must shift to M51.1- or M51.36x/M51.37x.
Document the pain radiation pattern explicitly: 'pain radiates from the lumbar spine down the left leg following the sciatic nerve distribution' distinguishes M54.42 from isolated low back pain codes.
If conservative care has been tried, document prior treatments (PT, NSAIDs, injections) to support medical necessity for advanced imaging or procedural intervention.

Related CPT procedures

Procedure codes commonly billed with M54.42. Linking the right diagnosis to the right procedure is what establishes medical necessity.

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

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.

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.

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.

97110 $29.06

Therapeutic exercise billed per 15-minute unit, targeting strength, endurance, range of motion, or flexibility with direct one-on-one patient contact.

62323 View procedure details

62321 View procedure details

97530 View procedure details

64483 View procedure details

64484 View procedure details

Common coding pitfalls

The recurring mistakes coders make with M54.42 and adjacent codes.

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

Assigning M54.42 when an intervertebral disc disorder is the confirmed cause — this violates the Excludes1 rule; use M51.1- instead.
Defaulting to M54.40 (unspecified side) when laterality is clearly documented in the note — always report the most specific code supported by documentation.
Confusing M54.42 with M54.32 (sciatica, left side only) — M54.42 requires both lumbago and left sciatica to be documented; if the provider only documents radicular leg pain without concurrent low back pain, M54.32 is correct.
Using M54.42 for bilateral sciatica with low back pain — no bilateral code exists in M54.4; M54.40 (unspecified) is the closest available option, but the bilateral presentation must be documented to justify the encounter.
Stacking M54.42 with M51.362 or M51.372 in the same encounter — these are Excludes1 exclusions and cannot be reported together.

Clinical context

Source · Editorial summary grounded in 5 cited references ↓

Use M54.42 when the provider documents both lumbar back pain and left-sided sciatica as a combined presentation, and no intervertebral disc disorder has been confirmed as the underlying cause. If imaging or clinical findings establish that a disc disorder is driving the sciatica, the correct code shifts to M51.1- (intervertebral disc degeneration with radiculopathy). Likewise, if discogenic back pain and lower extremity pain stem from lumbar or lumbosacral disc degeneration, use M51.362 or M51.372 respectively — both are Excludes1 exclusions at the M54.4 category level, meaning they cannot be coded alongside M54.42.

M54.42 is distinct from M54.32 (sciatica, left side without documented lumbago) and M54.40 (lumbago with sciatica, unspecified side). Laterality must be explicitly documented to justify M54.42 over M54.40. If the provider notes bilateral involvement, M54.40 is the closest available option since no bilateral-specific code exists in this subcategory.

This code groups to MS-DRG 551 (Medical back problems with MCC) or 552 (Medical back problems without MCC) under v43.0. It is valid for all care settings — orthopedic office, physical therapy, pain management, and emergency — and has been billable without revision since its introduction in FY2016.

Sibling codes

Other billable codes under M54.4 (laterality / anatomic variants).

M54.41

Lumbago with sciatica, right side

M54.40

Lumbago with sciatica, unspecified side

Frequently asked questions

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

01Can M54.42 and M51.12 be billed together for the same encounter?

No. M54.4- codes carry an Excludes1 note for lumbago with sciatica due to intervertebral disc disorder (M51.1-). If disc pathology is confirmed, use M51.12 (lumbar disc degeneration with radiculopathy) and drop M54.42 entirely.

02What is the difference between M54.42 and M54.32?

M54.32 is sciatica on the left side without documented low back pain. M54.42 requires both lumbago (low back pain) and left-sided sciatica to be present and documented together. Use the code that matches what the provider actually documented.

03If the patient has bilateral sciatica with low back pain, which code applies?

There is no bilateral-specific code in the M54.4 subcategory. M54.40 (lumbago with sciatica, unspecified side) is the closest option when bilateral involvement is documented, since M54.41 and M54.42 are laterality-specific and cannot both be assigned for the same episode.

04Does M54.42 require a 7th character extension?

No. M54.42 is a 5-character M-code under Chapter 13 (musculoskeletal). The A/D/S 7th-character extension convention applies to injury S-codes, not to dorsalgia M-codes.

05Is M54.42 appropriate when the diagnosis is documented as 'lumbar radiculopathy, left side'?

Not directly. Lumbar radiculopathy maps to M54.16 (radiculopathy, lumbar region). M54.42 is specific to lumbago with sciatica; use M54.16 when the provider's documented diagnosis is radiculopathy rather than sciatica with lumbago.

06What imaging documentation supports M54.42?

MRI or CT findings of nerve root compression or irritation at the lumbar level support the diagnosis but are not required for coding. If imaging shows a disc herniation as the cause, the code should shift to M51.1-. A clinical diagnosis based on SLR testing and symptom pattern is sufficient for M54.42 when no structural disc disorder is confirmed.

07Can M54.42 be used in physical therapy billing?

Yes. M54.42 is valid across all outpatient care settings including physical therapy. The PT must document left-sided sciatic pain distribution with concurrent low back pain, and the referring provider's diagnosis should align with the code selected.

Sources & references

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

Mira AI Scribe

Mira AI Scribe captures the laterality of sciatic pain (left), the lumbar pain location, SLR test result with the side tested, and any imaging findings with their interpretation — and flags when disc pathology is identified, prompting a code change to M51.1- before the claim is submitted. This prevents unspecified-side downcoding and Excludes1 violations that trigger payer denials.

See how Mira captures M54.42 documentation