Streptococcal joint infection involving multiple joints simultaneously, caused by streptococcal species other than group A (Streptococcus pyogenes) and group B (Streptococcus agalactiae), where no single joint site predominates.

Documentation tips

What should appear in the chart to support M00.29.

Source · Editorial brief grounded in 5 cited references ↓

• Explicitly document that multiple joints are involved — polyarthritis requires more than one joint to be infected; a single-joint streptococcal infection should be coded to the site-specific M00.2x code instead.
• Identify the streptococcal species or group in the assessment (e.g., Streptococcus group C, group G, or viridans group) so the correct B95.x companion code can be assigned.
• Record culture and sensitivity results in the chart — organism identification from joint aspirate or blood culture is what justifies M00.29 over a nonspecific infectious arthritis code.
• Document any comorbidities that qualify as CC or MCC (e.g., bacteremia, sepsis, immunocompromised state) to support the correct MS-DRG tier (548, 549, or 550).
• If the patient has a joint prosthesis in any of the affected joints, document whether the prosthesis itself is infected — that shifts coding to T84.5- and changes the code sequence.

Related CPT procedures

Procedure codes commonly billed with M00.29. Linking the right diagnosis to the right procedure is what establishes medical necessity.

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

Common coding pitfalls

The recurring mistakes coders make with M00.29 and adjacent codes.

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

• Omitting the required B95.0–B95.2 or B95.4–B95.5 companion code to identify the streptococcal agent — the tabular 'Use additional code' instruction is mandatory, not advisory.
• Using M00.29 when only one joint is involved — polyarthritis means multiple joints; a single-joint infection should be coded to the anatomically specific M00.2x child code (e.g., M00.261 for right knee).
• Confusing group A strep (covered under M00.0x Staphylococcal... — note: group A strep maps to M00.2 with B95.0) with other streptococcal species — verify the B95 code matches the documented organism group before finalizing.
• Billing M00.29 on a claim involving an infected internal joint prosthesis without addressing the T84.5- Excludes 2 note — the prosthesis infection may need to be the principal diagnosis.
• Failing to code sepsis (A40.x or A41.x) as a separate diagnosis when the provider documents streptococcal septic arthritis with systemic infection — sepsis codes are not included in M00.29.

Clinical context

Source · Editorial summary grounded in 5 cited references ↓

Sibling codes

Other billable codes under M00.2 (laterality / anatomic variants).