ICD-10 Code M79.602: Pain in Left Arm Coding Guide

Key Takeaways

ICD-10 Code M79.602 is the billable FY2026 code for Pain in left arm (Pain in left upper limb NOS), classified under Chapter XIII musculoskeletal disorders.

Use M79.602 only when no more specific musculoskeletal code is supported by documentation; shoulder pain and cervical radiculopathy have dedicated codes.

Providers must document that left arm pain has a musculoskeletal or non-cardiac etiology; cardiac rule-out is critical before applying this code.

Pabau’s claims management software helps physical therapy, chiropractic, and sports medicine clinics attach M79.602 accurately and reduce claim denials.

Left arm pain is one of the most common musculoskeletal complaints presenting in primary care, physical therapy, and sports medicine settings. It is also one of the most coding-sensitive: apply the wrong code, and claims are delayed, denied, or flagged for medical review. Apply a more specific code when documentation supports it, and you leave reimbursement potential on the table by using an overly broad code.

ICD-10 Code M79.602 covers “Pain in left arm” (inclusion term: Pain in left upper limb NOS) and sits within the M79 category of other and unspecified soft tissue disorders. This guide covers the official code definition, when to use it versus more specific alternatives, documentation requirements, related codes, the ICD-9 crosswalk, and billing considerations for clinics using this diagnosis in claims workflows.

ICD-10 Code M79.602: Definition and Clinical Description

ICD-10 Code M79.602 is a billable, specific diagnosis code valid for FY2026 claims submission. Its full official description, as listed in the CMS ICD-10-CM tabular list, is “Pain in left arm.” The inclusion term extends its scope to “Pain in left upper limb NOS” (not otherwise specified), meaning it applies when pain is located anywhere along the left upper limb but cannot be assigned to a more specific anatomical subsite or etiology.

The code sits within ICD-10-CM Chapter XIII: Diseases of the musculoskeletal system and connective tissue (M00-M99), under the M79 subcategory “Other and unspecified soft tissue disorders.” The parent category M79.6 covers pain in limb, hand, foot, fingers, and toes. M79.602 is the left-sided, arm-specific code within that parent group.

Per the CDC/NCHS ICD-10-CM web tool, M79.602 has been billable across every edition from 2016 through 2026, making it one of the stable, non-revised codes in the musculoskeletal chapter. Clinicians and coders using physical therapy EMR platforms can safely use this code for FY2026 without transition concerns.

When to Use ICD-10 Code M79.602

M79.602 is appropriate when left arm pain is the presenting complaint and clinical documentation does not support a more anatomically or etiologically specific code. The term “NOS” (not otherwise specified) is the operative signal: if the documentation specifies where exactly the pain originates or what is causing it, a more specific code almost certainly exists.

Common clinical scenarios where M79.602 is correctly applied include:

• Diffuse left arm pain without a clearly identified source structure
• Left upper limb pain following exertion where imaging and examination are inconclusive
• Post-minor-trauma left arm pain where no fracture, dislocation, or specific soft tissue injury is documented
• Left arm pain in a patient presenting for evaluation where the encounter note documents pain only without a definitive diagnosis
• Chronic non-specific left upper limb pain in occupational health or musculoskeletal screening settings

Cardiac rule-out is mandatory: Left arm pain can be a presenting symptom of acute myocardial infarction and other cardiac events. Providers must document the clinical basis for attributing the pain to a musculoskeletal or soft tissue etiology before applying M79.602. If cardiac origin has not been ruled out, M79.602 is not the appropriate code. Coders must never assign this code when documentation is ambiguous about whether the pain is cardiac or musculoskeletal in origin.

Specificity Requirement

ICD-10-CM guidelines require coders to assign the most specific code supported by documentation. M79.602 is appropriate only when documentation does not support a more specific code. If the provider documents shoulder pain, use M25.51-. If cervical radiculopathy is documented, use M54.12. If brachialgia is documented, use M54.12 or a more specific radiculopathy code. The underlying principle from ICD coding guidelines: default to the most specific code the documentation supports, not the most general code that is technically billable.

Related and Comparable Codes

Understanding M79.602 in context means knowing its adjacent codes in the M79.6 family and the codes that may be more specific for a given presentation. Coders at chiropractic software-supported clinics frequently work across this code range when evaluating upper limb pain.

A key distinction: M79.622 (Pain in left upper arm) is more specific than M79.602 and should be used when the provider’s note documents that the pain is localized to the upper arm, as opposed to the full limb. Coders should review notes carefully for phrases like “left upper arm,” “left forearm,” or “left elbow region,” as each has a corresponding more specific code that supersedes the general M79.602. Use AAPC’s Codify ICD-10-CM lookup to verify the full M79 code range when auditing claims.

Documentation Requirements for M79.602

Payers reviewing claims coded with M79.602 look for documentation that justifies the non-specific nature of the diagnosis. Claims without adequate documentation are frequently flagged for medical necessity review or denied. Clinics using sports medicine software or musculoskeletal EHR platforms need to ensure their clinical notes capture each of the following elements.

• Pain location: Document that pain involves the left arm or left upper limb. Avoid vague descriptions like “arm pain” without specifying laterality.
• Onset and duration: Acute versus chronic pain documentation supports medical necessity and may affect sequencing rules.
• Character and severity: Quality (aching, sharp, burning), severity scale, and any aggravating or relieving factors.
• Absence of more specific etiology: The note should reflect that no specific structural cause (shoulder pathology, nerve root involvement, fracture) has been identified, justifying the non-specific code.
• Cardiac rule-out documentation: For any patient where cardiac origin is a clinical concern, the note must document that cardiac causes have been considered and excluded or are under separate investigation.
• Physical examination findings: Range of motion, palpation, neurological screening, or functional testing that supports a musculoskeletal presentation.

Incomplete documentation is the primary driver of denials for M79.602 claims. Providers who capture structured notes through osteopathy practice software or EHR systems with templated musculoskeletal assessment fields reduce the risk of missing these elements at the point of care.

Coding Guidelines and Sequencing Rules

M79.602 follows standard ICD-10-CM sequencing rules. When left arm pain is the primary reason for the encounter, it should be listed as the principal diagnosis. When it accompanies a more specific condition, sequencing depends on whether the pain is an integral part of the underlying condition or a separately documented symptom.

Two sequencing scenarios arise most often in practice:

1. Pain as the primary reason for the encounter: When a patient presents specifically for left arm pain and no definitive diagnosis is established at the encounter, M79.602 is sequenced first. This is the most common scenario in initial evaluation visits.
2. Pain as a secondary finding: When the encounter is primarily for a specific condition (e.g., rotator cuff evaluation) and left arm pain is a separately documented, clinically relevant symptom not integral to that condition, M79.602 may be added as an additional code.

Per ICD-10-CM guidelines, signs and symptoms that are integral to a definitive diagnosis should not be coded separately. If a provider documents “left arm pain due to cervical radiculopathy,” the pain code M79.602 should not be added because it is integral to the radiculopathy diagnosis (M54.12). Clinics should configure their digital intake forms to capture laterality and symptom specificity from patients at the point of registration, reducing documentation gaps that cause sequencing errors downstream.

Excludes Notes

The M79.6 parent category (Pain in limb, hand, foot, fingers and toes) carries an official Excludes2 note in the FY2026 ICD-10-CM tabular list: pain in joint (M25.5-). An Excludes2 note signals that the excluded condition is not part of the code being reported, but the patient may have both conditions concurrently. If a patient has both diffuse left arm pain and a documented joint pain in the same encounter (for example, a coexisting shoulder joint pain), both codes can be reported together when each is independently supported by documentation.

Specific Excludes notes coders should verify against the current CMS tabular list for M79.602:

• Excludes2 from M79.6: Pain in joint (M25.5-). Use M25.512 for left shoulder joint pain, M25.522 for left elbow joint pain, or M25.532 for left wrist joint pain when the documentation localizes pain to a specific joint.
• Chapter XIII Excludes1: Compartment syndrome (traumatic) (T79.A-), arthropathic psoriasis (L40.5-), and certain conditions originating in the perinatal period (P04-P96) are excluded from the entire musculoskeletal chapter and cannot be coded with M79.602 for the same condition.
• Chapter XIII Excludes2: Symptoms, signs, and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94) may coexist when documentation supports each separately.
• Practical exclusions to watch for: If the documentation supports a more specific musculoskeletal diagnosis (myalgia M79.1, cervical radiculopathy M54.12, rotator cuff syndrome M75.1-), that code supersedes M79.602 under the “code to highest specificity” rule.

Coders should always verify the current-year tabular list using the CDC/NCHS ICD-10-CM web tool because Excludes notes can change between fiscal years. As of FY2026, the M25.5- Excludes2 entry under M79.6 remains the primary exclusion clinicians and billers must navigate when coding left arm pain.

Streamline Musculoskeletal Documentation with Pabau

Pabau helps physical therapy, chiropractic, and sports medicine clinics capture structured clinical notes, attach ICD-10 codes accurately, and submit clean claims. Reduce denials and improve coding compliance with purpose-built tools for musculoskeletal practice workflows.

Book a demo

ICD-9-CM Crosswalk and Historical Context

Before the US transition to ICD-10-CM in October 2015, left arm pain was coded using ICD-9-CM 729.5, “Pain in limb.” This was a non-lateralized, non-limb-specific code that covered pain across all four limbs. The ICD-10-CM expansion introduced laterality and anatomical specificity that ICD-9-CM lacked entirely.

The approximate crosswalk from ICD-10-CM M79.602 back to ICD-9-CM is 729.5. This mapping is approximate because ICD-9-CM 729.5 applied to any limb, while M79.602 is left-arm-specific. When reviewing historical claims or conducting retrospective chart reviews, clinics should note that any limb pain coded as 729.5 could represent what would now be coded as M79.601, M79.602, M79.609, or any of a dozen more specific musculoskeletal codes depending on documentation specificity. Research databases like ResDAC’s Medicare claims data resources provide guidance on working with ICD-9 to ICD-10 transitions in longitudinal datasets.

Practices that transitioned from older billing systems and are now working through claim corrections or appeals involving pre-2015 encounters will need to apply this approximate crosswalk carefully. Pabau’s claims management software supports documentation of both current ICD-10 codes and historical reference notes within patient records, helping billing teams manage crosswalk-related corrections without losing audit trail integrity.

Billing and Reimbursement Considerations

M79.602 is a valid diagnosis code for pairing with evaluation and management (E&M) CPT codes, physical therapy procedure codes, and musculoskeletal diagnostic imaging codes. The most common CPT code pairings seen in practice include 99213 and 99214 for office visits, 97110 for therapeutic exercise, and musculoskeletal ultrasound codes when imaging is performed during the encounter.

Several billing considerations apply specifically to M79.602 claims:

• Medical necessity: Payers require documentation demonstrating that the services billed were medically necessary for the coded diagnosis. Non-specific pain codes like M79.602 face higher scrutiny, particularly for high-complexity E&M visits or extended therapy sessions. Documentation must show clinical justification proportional to the services billed.
• Prior authorization: Some payers require prior authorization for physical therapy services beyond a defined number of visits, even when M79.602 is correctly applied. Verify payer-specific requirements before initiating extended treatment courses.
• Specificity over cycles: If a patient continues presenting over multiple encounters, the diagnosis should evolve with clinical findings. Persistently coding M79.602 across many visits without progressing to a more specific diagnosis as workup advances may attract payer review.
• Bilateral coding: If both arms are affected, code each arm separately using M79.601 (right arm) and M79.602 (left arm). Do not use M79.609 (unspecified) when laterality is documented for both sides.

Clinics handling musculoskeletal billing across multiple providers benefit from structured coding workflows. Platforms with integrated ICD-10 coding reference tools that surface related codes at the time of documentation help providers choose between M79.602 and its more specific counterparts before the claim is submitted.

Common CPT Codes Used with M79.602

M79.602 supports medical necessity for a wide range of evaluation, treatment, and diagnostic services across primary care, physical therapy, sports medicine, and chiropractic settings. The table below summarizes the CPT codes most frequently paired with M79.602 in outpatient claims, along with documentation considerations for each pairing. Coders should always confirm payer-specific edit pairs and Local Coverage Determinations (LCDs) before submission.

For EMG codes 95885 and 95886, payers typically require documentation that connects the upper-limb pain presentation to a specific nerve-related differential (suspected radiculopathy, brachial plexopathy, or peripheral neuropathy) before authorizing the test. When EMG is normal, M79.602 can support the encounter; when EMG identifies a specific neuropathy, the more specific diagnosis code should replace M79.602 going forward. Imaging codes in the 73000-series follow similar logic: M79.602 supports the imaging order when the location within the limb is unclear, but specific codes (M79.622 for upper arm, M25.512 for shoulder, S43- or S46- for traumatic injuries) supersede when documentation localizes the source.

Coding M79.602 in Specific Clinical Settings

How M79.602 is applied varies meaningfully by clinical setting. The pain etiology, the typical diagnostic workup, and the payer mix shape both code selection and documentation expectations. The subsections below outline how physical therapy, sports medicine, chiropractic, and primary care or urgent care clinics typically encounter and code left arm pain.

Physical Therapy

Physical therapy clinics see M79.602 most frequently as a referring diagnosis when a primary care physician or orthopedist has not yet established a structural diagnosis. The PT evaluation (97161-97163) often refines the diagnosis: if the therapist identifies rotator cuff involvement, the working diagnosis should advance to M75.1- by the next note. If the PT documents diffuse tightness without a specific structural finding, M79.602 remains appropriate. Therapists should pair M79.602 with functional outcome measures (DASH, QuickDASH, Patient-Specific Functional Scale) to satisfy payer requirements for medical necessity, especially for extended courses of care. Therapeutic exercise (97110), manual therapy (97140), and therapeutic activities (97530) are the most common procedure pairings. Physical therapy EMR systems with structured assessment templates help therapists capture the laterality, region, and functional status data that supports M79.602 claims.

Sports Medicine

Sports medicine clinics encounter left arm pain in athletes presenting with overuse syndromes, post-training discomfort, and acute injuries where imaging has ruled out a fracture or specific soft-tissue lesion. M79.602 is appropriate during the early diagnostic phase when symptoms are diffuse and structural pathology has not yet been demonstrated. As workup progresses, the diagnosis typically refines toward more specific codes: M75.1- (rotator cuff syndrome), M77.1- (lateral epicondylitis), or M77.2- (medial epicondylitis) for tendinopathies; S46- codes for documented muscle or tendon injuries. Sports medicine documentation should capture sport, training load, mechanism of injury (or absence of one), and prior episodes of similar pain. CPT pairings are typically 99203-99204 for new patient evaluations and 99213-99214 for follow-ups. Practices using sports medicine software benefit from templates that prompt for sport-specific aggravators and biomechanical assessment findings.

Chiropractic

Chiropractic care for left arm pain typically focuses on the cervical or thoracic spine as a referred-pain source, but M79.602 may be reported when the upper-limb pain itself is the presenting complaint and no specific cervicogenic, joint, or radicular origin is established at the initial visit. For Medicare claims, chiropractors must report a primary subluxation code (M99.01- or M99.02-) when billing chiropractic manipulative treatment (98940-98942); M79.602 may be reported as a secondary diagnosis describing the symptomatic presentation. Documentation should describe spinal segment findings, palpation results, and the relationship between the spinal subluxation and the upper-limb pain. As workup progresses, more specific codes (M54.12 cervical radiculopathy, M53.1 cervicobrachial syndrome) typically replace M79.602 when the referred-pain pathway is clinically established.

Primary Care and Urgent Care

Primary care and urgent care clinics are the most common point of first contact for patients with left arm pain. M79.602 frequently serves as the working diagnosis at the initial encounter, especially when cardiac etiology has been clinically excluded but no specific musculoskeletal cause has been identified. Documentation must capture the cardiac rule-out reasoning explicitly: relevant history, vital signs, ECG findings if obtained, and the clinical rationale for attributing the pain to a non-cardiac etiology. CPT pairings are typically 99202-99205 for new patients and 99212-99215 for established patients. When imaging is ordered, codes in the 73000-series support the encounter; when EMG is ordered to rule out radiculopathy, 95885 or 95886 are commonly paired. If symptoms persist beyond the initial workup without progressing to a more specific diagnosis, primary care providers should re-evaluate the differential and consider referral to physical therapy, sports medicine, or orthopedics. GP clinic software with integrated coding prompts helps primary care teams advance the diagnosis as workup progresses, rather than carrying M79.602 across multiple visits without clinical evolution.

Clinical Workflow Integration

The accuracy of M79.602 coding depends on how documentation is captured at the point of care. Practices where providers dictate notes into a general-purpose template frequently miss the specificity markers that distinguish M79.602 from M79.622 or shoulder-specific codes. Structured intake and assessment workflows solve this problem upstream.

Effective workflow integration typically involves three practice-level changes:

1. Structured laterality capture at intake: Patient intake forms that prompt laterality (left/right/bilateral) and body region (upper arm/forearm/full arm) give providers the raw material to code accurately. A well-structured ICD-10 documentation workflow starts before the patient sees the clinician.
2. Clinical note templates with specificity prompts: EHR templates that include checkboxes or drop-downs for “Pain localized to upper arm” versus “diffuse arm pain” guide providers toward documentation that supports coding decisions without adding clinical burden.
3. Coder review at claim preparation: A secondary review step where a coder checks whether M79.602 is still the most specific code supported by the completed note catches specificity errors before submission.

Practices using Pabau can leverage the client record management system to maintain longitudinal documentation of symptom evolution, which supports the transition from non-specific codes like M79.602 to more specific diagnoses as clinical workup progresses. This is particularly valuable in chronic pain presentations where coding must reflect the changing clinical picture across multiple encounters.

For clinics that treat musculoskeletal conditions alongside other specialties, maintaining accurate related ICD-10 diagnosis codes in the patient record creates an auditable history of the diagnostic reasoning process, which supports appeals if claims are denied and demonstrates medical necessity patterns to payers over time.

Expert Picks

Billing musculoskeletal services alongside physical therapy? Physical Therapy EMR by Pabau provides purpose-built documentation and claims tools for PT clinics handling musculoskeletal ICD-10 coding workflows.

Running a chiropractic or osteopathy clinic? Pabau Chiropractic Software supports structured assessment documentation, code capture, and claims submission for musculoskeletal presentations.

Need to manage compliance documentation for musculoskeletal patients? Mandatory Compliance for Physiotherapy Clinics outlines the documentation standards that protect your practice during payer audits.

Conclusion

Most M79.602 claim errors trace back to documentation, not coding. Providers document left arm pain in general terms; coders apply the general code; payers flag it for review or deny it for insufficient specificity. The fix is upstream: structured clinical notes that capture laterality, localization, and rule-out reasoning at the point of care.

Pabau’s client record and claims management tools help musculoskeletal clinics build those documentation habits into standard workflows. From structured intake forms that capture laterality to claims review workflows that surface more specific code alternatives before submission, the platform reduces the gap between how providers document and what billers need. To see how Pabau handles musculoskeletal documentation and claims workflows for physical therapy, chiropractic, and sports medicine practices, book a demo.

Frequently Asked Questions