M00.19

M00.19 identifies pneumococcal pyogenic arthritis involving multiple joints simultaneously, caused by Streptococcus pneumoniae infection, where no single dominant joint site can be specified.

Verified May 8, 2026 · 4 sources ↓

Status: Billable
Chapter: 13
Related CPT: 10
Region: Multi-region

Drawn from CDCICD10DataAAPCCMS

Documentation tips

What should appear in the chart to support M00.19.

Source · Editorial brief grounded in 4 cited references ↓

Confirm the pathogen in the medical record — M00.19 requires documentation of Streptococcus pneumoniae (pneumococcus) as the causative organism, ideally via culture or lab report.
List every affected joint explicitly; 'polyarthritis' is valid only when multiple joints are involved and no single site dominates the clinical picture warranting a site-specific M00.1x code.
Capture all comorbidities thoroughly — MCC/CC documentation determines whether the claim lands in MS-DRG 548, 549, or 550, which carry different reimbursement weights.
If joint aspiration or arthroscopic washout was performed, link the procedure code to M00.19 as the supporting diagnosis.
Document whether the infection is related to a prosthetic joint — if so, M00.19 is excluded and T84.5- applies instead.

Related CPT procedures

Procedure codes commonly billed with M00.19. Linking the right diagnosis to the right procedure is what establishes medical necessity.

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

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.

20604 $87.18

Arthrocentesis, aspiration and/or injection of a small joint or bursa (e.g., fingers, toes) performed with ultrasound guidance, including permanent image recording and reporting.

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.

20606 $94.19

Aspiration and/or injection of an intermediate joint or bursa — such as the wrist, elbow, ankle, acromioclavicular, temporomandibular, or olecranon bursa — performed with real-time ultrasound guidance and permanent image recording and reporting.

20610 $68.81

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

20611 $104.21

Aspiration or injection of a major joint or bursa performed under real-time ultrasound guidance, with permanent image documentation.

29870 $602.89

Diagnostic arthroscopy of the knee, with or without synovial biopsy — a separate procedure designation meaning it bundles into any same-session surgical knee arthroscopy.

29871 $491.33

Arthroscopic surgical procedure on the knee performed specifically to treat infection, including joint lavage (washout) and drainage of infected material.

86588 View procedure details

87071 View procedure details

Common coding pitfalls

The recurring mistakes coders make with M00.19 and adjacent codes.

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

Assigning M00.19 when only one joint is infected — use the site-specific laterality code (e.g., M00.161 right knee, M00.162 left knee) instead of the polyarthritis code.
Using M00.19 for pneumococcal prosthetic joint infection — the M00 Excludes2 directs prosthetic joint infections to T84.5-, not M00.19.
Defaulting to M00.10 (pneumococcal arthritis, unspecified joint) when multiple joints are clearly documented — M00.19 is the correct polyarthritis code and is more specific.
Confusing M00.19 (infectious, bacterial) with M15.x (polyosteoarthritis, degenerative) — these are clinically and structurally distinct categories; do not conflate inflammatory septic arthritis with degenerative joint disease.

Clinical context

Source · Editorial summary grounded in 4 cited references ↓

Use M00.19 when documentation confirms Streptococcus pneumoniae as the causative organism and the infection affects multiple joints — not a single, laterality-specific site. This is the polyarticular variant of pneumococcal arthritis under the M00.1x family. If the infection is isolated to one joint, select the site-specific code instead (e.g., M00.161 for right knee, M00.151 for right hip).

M00.19 sits within the pyogenic arthritis category (M00) under Chapter 13 of ICD-10-CM. The Excludes2 note at M00 bars its use when infection and inflammatory reaction are due to an internal joint prosthesis — route to T84.5- for prosthetic joint infections. There is no 7th-character extension required for M00.19; M-codes do not use the A/D/S encounter extension convention.

For MS-DRG assignment, M00.19 maps to DRG 548 (Septic Arthritis with MCC), 549 (with CC), or 550 (without CC/MCC) depending on comorbidity documentation. Accurate secondary diagnoses drive which DRG tier is assigned — comorbidity capture directly affects reimbursement level.

Sibling codes

Other billable codes under M00.1 (laterality / anatomic variants).

M00.18

Pneumococcal arthritis, vertebrae

M00.10

Pneumococcal arthritis, unspecified joint

Frequently asked questions

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

01When should I use M00.19 instead of a site-specific M00.1x code?

Use M00.19 only when pneumococcal arthritis is documented in multiple joints and no single site is the exclusive focus. If one joint is infected, select the appropriate site-specific code with laterality (e.g., M00.161 for right knee).

02Does M00.19 require a 7th-character extension for initial vs. subsequent encounter?

No. The A/D/S 7th-character convention applies to injury S-codes, not to M-category musculoskeletal codes. M00.19 is valid as a 5-character code with no extension needed.

03Can M00.19 be used if the patient has a prosthetic joint among the affected sites?

No. The Excludes2 note at M00 directs prosthetic joint infections to T84.5-. If a prosthetic joint is involved, that site must be coded separately under T84.5-; M00.19 may still apply to native joints in the same encounter, but clarify documentation.

04Which MS-DRGs does M00.19 map to?

M00.19 groups to MS-DRG 548 (Septic Arthritis with MCC), 549 (with CC), or 550 (without CC/MCC) per CMS MS-DRG v43.0. The tier depends on documented comorbidities and complications.

05Is M00.19 valid as a primary diagnosis on an outpatient claim?

Yes, M00.19 is a billable, specific code valid for outpatient and inpatient use. Ensure the causative organism is documented; payer medical necessity requirements for any associated procedure must also be met.

06What is the difference between M00.19 and M15.x?

M00.19 is infectious septic arthritis caused by Streptococcus pneumoniae affecting multiple joints. M15.x codes degenerative polyosteoarthritis with no bacterial etiology. These are mutually exclusive etiologies — do not interchange them.

07Are there approximate synonyms for M00.19 that coders should recognize in documentation?

Yes. Per ICD-10 data, accepted synonyms include 'Pneumococcal arthritis and polyarthritis' and 'Pneumococcal arthritis of multiple joints.' Either phrasing in the clinical note supports M00.19.

Sources & references

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

01CDC ICD-10-CM Tabular List 2026 (FY2026, effective Oct 1, 2025)
02
icd10data.com
https://www.icd10data.com/ICD10CM/Codes/M00-M99/M00-M02/M00-/M00.19
03
aapc.com
https://www.aapc.com/codes/icd-10-codes/M00.19
04
cms.gov
https://www.cms.gov/icd10m/version372-fullcode-cms/fullcode_cms/P0214.html

Mira AI Scribe

Mira AI Scribe captures the treating clinician's documentation of multiple affected joints, the confirmed pneumococcal organism (culture result, lab reference, or clinical statement), absence of prosthetic hardware at infected sites, and any comorbidities relevant to MCC/CC tier assignment. This prevents downcode to the less specific M00.10 (unspecified joint) and avoids an audit flag for missing organism identification.

See how Mira captures M00.19 documentation