M02.80

M02.80 identifies reactive arthritis caused by an infection elsewhere in the body — falling outside the specific Reiter's disease or postdysenteric categories — when no joint site is documented or determinable.

Verified May 8, 2026 · 4 sources ↓

Status: Billable
Chapter: 13
Related CPT: 5
Region: General

Drawn from CDCICD10DataAAPCCMS

Documentation tips

What should appear in the chart to support M02.80.

Source · Editorial brief grounded in 4 cited references ↓

Identify and document the specific triggering infection (e.g., chlamydial urethritis, gonorrhea) so the etiologic code can be sequenced first ahead of M02.80.
Record the joint site and laterality in the clinical note; if site is identified, a site-specific M02.8x code is required instead of M02.80.
Document the temporal relationship between the confirmed infection and joint inflammation onset — insurers may request this to distinguish reactive arthritis from septic arthritis.
Note any lab results (STI panel, culture, urinalysis) or imaging that support a reactive rather than infectious etiology directly within the joint.
Confirm the diagnosis does not meet criteria for Reiter's disease (M02.3x) or postdysenteric arthropathy (M02.1x) before defaulting to M02.80.

Related CPT procedures

Procedure codes commonly billed with M02.80. 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.

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.

73564 $49.43

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

71046 View procedure details

Common coding pitfalls

The recurring mistakes coders make with M02.80 and adjacent codes.

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

Sequencing M02.80 as the principal/first-listed code instead of the underlying infectious etiology code violates the etiology/manifestation convention and risks claim denial.
Using M02.80 when a specific joint site is documented in the record — the site-specific sibling codes under M02.8 should be used whenever laterality or joint location is available.
Confusing reactive arthritis with septic (infectious) arthritis: M02.80 groups into MS-DRGs 548–550 (septic arthritis), so payer scrutiny is elevated — confirm the organism is not directly infecting the joint.
Failing to code the triggering infection at all, leaving the claim without the required etiology code that M02.80 depends on for correct sequencing.
Defaulting to M02.80 for Reiter's disease or postdysenteric arthropathy cases, which have their own distinct subcategories (M02.3x and M02.1x respectively).

Clinical context

Source · Editorial summary grounded in 4 cited references ↓

M02.80 is the unspecified-site code within the 'other reactive arthropathies' subcategory (M02.8). Use it when the clinical record confirms a reactive arthritis pattern linked to a triggering infection (most commonly genitourinary) but does not specify or document which joint is affected. The approximate synonyms flagged by CMS include post-genitourinary infection reactive arthritis and reactive arthritis after genitourinary infection.

This code is a manifestation code, meaning the underlying infectious trigger should be coded and sequenced first per the etiology/manifestation convention in the ICD-10-CM Official Guidelines. M02.80 follows that primary etiologic code on the claim. Skipping the etiology code or sequencing M02.80 first is a sequencing error that can trigger a denial or audit flag.

When the affected joint site is documented, move to the site-specific sibling codes (M02.81 shoulder, M02.82 elbow, and so on). M02.80 is only appropriate when site documentation is genuinely absent — not as a shortcut when laterality or joint site is available in the record. For reactive arthritis defined as Reiter's disease, use M02.3x instead; for postdysenteric reactive arthropathy, use M02.1x.

Sibling codes

Other billable codes under M02.8 (laterality / anatomic variants).

M02.88

Other reactive arthropathies, vertebrae

M02.89

Other reactive arthropathies, multiple sites

Frequently asked questions

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

01When should I use M02.80 instead of a site-specific M02.8x code?

Use M02.80 only when the affected joint site is genuinely not documented. If the record names any specific joint — shoulder, knee, ankle, etc. — use the corresponding site-specific code (M02.81–M02.89) instead.

02Does M02.80 require a second code for the underlying infection?

Yes. M02.80 is a manifestation code. Per the etiology/manifestation convention, the code for the underlying infectious condition must be sequenced first; M02.80 follows as the secondary diagnosis.

03How does M02.80 differ from M02.3x (Reiter's disease)?

Reiter's disease (M02.3x) is a defined triad of arthritis, urethritis, and conjunctivitis. M02.80 applies to other reactive arthropathies — typically post-genitourinary infection — that do not meet the full Reiter's criteria.

04Why does M02.80 group into the septic arthritis MS-DRGs (548–550)?

CMS DRG logic places M02.80 into MS-DRGs 548–550 because reactive arthritis can overlap clinically with septic arthritis presentations. This means payers will scrutinize claims — documentation must clearly support that the joint itself is not directly infected.

05Can M02.80 be used as a primary diagnosis in the outpatient setting?

Only if the infectious etiology is coded separately and sequenced before it. M02.80 as a standalone first-listed code without an accompanying etiologic infection code is a sequencing violation under ICD-10-CM Official Guidelines.

06Is M02.80 appropriate for postdysenteric reactive arthropathy?

No. Postdysenteric reactive arthropathy has its own subcategory at M02.1x. Use M02.80 only for 'other' reactive arthropathies — primarily those triggered by genitourinary infection — not for enteric/dysenteric triggers.

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-/M02.80
03
aapc.com
https://www.aapc.com/codes/icd-10-codes/M02.80
04
cms.gov
https://www.cms.gov/files/document/fy-2025-icd-10-cm-coding-guidelines.pdf

Mira AI Scribe

The Mira AI Scribe captures the implicated triggering infection (organism, site, encounter date), the joint(s) reported by the patient, and any lab or imaging findings that distinguish reactive from septic arthritis. This ensures the etiologic code is available for correct first-position sequencing ahead of M02.80 and prevents a manifestation-code sequencing error that would flag on audit.

See how Mira captures M02.80 documentation