M02.39

Reiter's disease (reactive arthritis) affecting multiple joint sites simultaneously, coded when two or more anatomically distinct joints are involved and no single-site code captures the full clinical picture.

Verified May 8, 2026 · 6 sources ↓

Status: Billable
Chapter: 13
Related CPT: 14
Region: Multi-region

Drawn from CDCICD10DataAAPCCMS

Documentation tips

What should appear in the chart to support M02.39.

Source · Editorial brief grounded in 6 cited references ↓

List every affected joint by name and side — e.g., 'bilateral knees and right ankle' — to justify the multiple-sites code over a single-site alternative.
Document the antecedent infection (genitourinary or GI) with onset date and type to establish the reactive arthritis causation; add a B95–B97 code if the organism is identified.
Record the classic triad components that are present (arthritis, urethritis, conjunctivitis) even if incomplete, as this distinguishes Reiter's disease from other reactive arthropathies.
Note inflammatory markers (ESR, CRP, WBC) and synovial fluid analysis results when joint aspiration is performed — these support medical necessity for procedures billed alongside M02.39.
If the provider uses the term 'reactive arthritis' rather than 'Reiter's disease,' coding is unchanged — the Applicable To note under M02.3 maps both terms to this subcategory.

Related CPT procedures

Procedure codes commonly billed with M02.39. Linking the right diagnosis to the right procedure is what establishes medical necessity.

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

20610 $68.81

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

20600 $56.11

Needle aspiration and/or injection of a small joint or bursa — such as a finger or toe joint — performed without ultrasound guidance.

20605 $57.12

Aspiration and/or injection of an intermediate joint or bursa — such as the wrist, elbow, ankle, acromioclavicular joint, or olecranon bursa — performed without ultrasound guidance.

73564 $49.43

Radiologic examination of the knee consisting of four or more views, including oblique and tunnel projections, for a complete diagnostic workup.

73562 $42.42

Three-view radiographic examination of the knee joint, capturing anteroposterior, lateral, and a third angle such as a sunrise or oblique view.

73560 $34.40

Radiologic examination of the knee joint, one or two views, unilateral.

73630 $34.07

Radiologic examination of the foot requiring a minimum of three views, used to evaluate fractures, arthritis, tumors, or structural abnormalities.

73620 $28.72

Radiologic examination of the foot, two views — used to evaluate bone and joint abnormalities including fractures, arthritis, and structural deformities.

73610 $37.07

Radiologic examination of the ankle joint requiring a minimum of three views, used to evaluate bone structure, alignment, and soft-tissue abnormalities.

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.

99215 $192.39

Highest-level office or outpatient E/M visit for an established patient, qualifying via high-complexity medical decision making or 40–54 minutes of total provider time on the date of service.

27369 $181.70

Injection of contrast material into the knee joint in preparation for contrast knee arthrography, contrast-enhanced CT arthrography, or contrast-enhanced MRI arthrography.

27370 View procedure details

Common coding pitfalls

The recurring mistakes coders make with M02.39 and adjacent codes.

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

Billing parent code M02.3 instead of M02.39 — M02.3 is non-billable; always use a fully specified child code.
Defaulting to M02.30 (unspecified site) when the note clearly documents multiple joints — M02.39 is the correct specificity when multi-site involvement is documented.
Assigning M02.39 alongside an Excludes1 condition such as Behçet's disease (M35.2) or a direct joint infection from M01.- — these are mutually exclusive; review the Excludes1 list at the M02 block before coding.
Omitting the infectious agent code (B95–B97) when the triggering organism is documented — this leaves clinically available specificity on the table and may affect payer review.
Using a single-site Reiter's code (e.g., M02.361) when the encounter addresses two or more distinct joints — that undercodes the clinical complexity and may not support the level of E/M billed.

Clinical context

Source · Editorial summary grounded in 6 cited references ↓

M02.39 applies when Reiter's disease — a reactive arthritis triggered by a preceding genitourinary or gastrointestinal infection — is documented as affecting multiple joints rather than a single, specifiable site. The classic triad of arthritis, urethritis, and conjunctivitis may be present, but the diagnosis does not require all three components. Use M02.39 only when the provider explicitly documents multi-site joint involvement; if a single joint is the primary focus, select the site-specific code (e.g., M02.361 for right knee, M02.371 for right ankle and foot).

M02.39 sits under parent code M02.3 (Reiter's disease / reactive arthritis), which carries an Applicable To note mapping 'reactive arthritis' to this subcategory. The M02 block carries Excludes1 instructions ruling out Behçet's disease (M35.2), direct joint infections in infectious/parasitic diseases classified elsewhere (M01.-), postmeningococcal arthritis (A39.84), mumps arthritis (B26.85), rubella arthritis (B06.82), late syphilitic arthritis (A52.77), rheumatic fever (I00), and tabetic arthropathy (A52.16). Verify none of those conditions is the correct primary diagnosis before assigning M02.39.

In orthopedic practice, Reiter's disease presenting at multiple joints — commonly knees, ankles, and small joints of the feet — may prompt joint aspiration, imaging, and rheumatology co-management. A code from B95–B97 may be added to identify the causative infectious agent when documented. Do not use parent code M02.3 for billing; it is non-billable. M02.30 (unspecified site) is the fallback only when no site is documented at all — not a substitute for M02.39 when multiple sites are clearly noted.

Sibling codes

Other billable codes under M02.3 (laterality / anatomic variants).

M02.38

Reiter's disease, vertebrae

M02.30

Reiter's disease, unspecified site

Frequently asked questions

Source · Generated from the editorial pipeline, verified against 6 cited references ↓

01When should I use M02.39 instead of a single-site Reiter's code?

Use M02.39 when the provider documents active involvement of two or more anatomically distinct joints. If only one joint is actively treated or documented, select the site-specific code (e.g., M02.361 right knee, M02.371 right ankle and foot).

02Is 'reactive arthritis' coded the same as 'Reiter's disease' in ICD-10-CM?

Yes. The Applicable To note under parent code M02.3 explicitly maps 'reactive arthritis' to the Reiter's disease subcategory. M02.39 is correct for multi-site reactive arthritis regardless of which term the provider uses.

03Do I need to code the triggering infection separately?

When the causative organism is documented, add a code from B95–B97 to identify the infectious agent. This is a Use Additional Code instruction at the M02 block level and provides clinically relevant specificity for payer and quality reporting purposes.

04Can M02.39 be assigned with Behçet's disease (M35.2) on the same claim?

No. Behçet's disease (M35.2) is listed as an Excludes1 condition at the M02 block, meaning it cannot be coded simultaneously with M02.39. If the diagnosis is Behçet's, use M35.2 instead.

05What is the difference between M02.39 and M02.30?

M02.30 is for Reiter's disease at an unspecified site — use it only when the provider documents no specific joint involvement. M02.39 is the correct code when multiple sites are explicitly documented.

06Does M02.39 require a 7th-character extension?

No. M02.39 is a 5-character M-code and does not use 7th-character extensions. The A/D/S encounter-type extensions apply to injury S-codes, not to musculoskeletal disease codes in Chapter 13.

07Which CPT codes are commonly billed with M02.39 in an orthopedic setting?

Joint aspiration and injection codes (20610 for a major joint, 20605 for an intermediate joint, 20600 for a small joint) and plain radiograph codes (e.g., 73564 knee AP/lateral/oblique, 73630 foot complete) are frequently paired with M02.39 when evaluation and treatment of affected joints is performed.

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/M00-M02/M02-/M02.39
03
icd10data.com
https://www.icd10data.com/ICD10CM/Codes/M00-M99/M00-M02/M02-/M02.3
04
aapc.com
https://www.aapc.com/codes/icd-10-codes/M02.39
05
cms.gov
https://www.cms.gov/medicare-coverage-database/view/article.aspx?articleid=55639
06
cms.gov
https://www.cms.gov/medicare-coverage-database/view/article.aspx?articleid=53057

Mira AI Scribe

Mira's AI scribe captures the number and names of affected joints with laterality, the documented preceding infection (type, organism if known, onset date), the presence or absence of urethritis and conjunctivitis, inflammatory lab values, and any synovial fluid findings. This level of detail prevents downcoding to the unspecified-site fallback M02.30, supports medical necessity for joint aspiration CPT codes billed on the same date, and satisfies payer requests for documentation linking the arthritis to a reactive etiology.

See how Mira captures M02.39 documentation