Infective bursitis occurring at an anatomical site not captured by any other specific M71.1x code — the true residual 'other site' bucket for organism-driven bursal inflammation.
Verified May 8, 2026 · 5 sources ↓
- Status
- Billable
- Chapter
- 13
- Related CPT
- 5
- Region
- Other
Documentation tips
What should appear in the chart to support M71.18.
Source · Editorial brief grounded in 5 cited references ↓
- Name the specific bursa involved (e.g., ischial, iliopsoas, infrapatellar) — 'other site' must be clinically justified by the absence of a more specific code.
- Document the infectious etiology explicitly: culture results, Gram stain, aspiration findings, or clinical diagnosis of septic bursitis — vague 'bursitis' without infectious qualifier will not support M71.18.
- Always co-code the causative organism using B95.– (staph/strep) or B96.– (other bacteria) per the M71.1 Use Additional Code instruction; this pairing is mandatory, not optional.
- Record prior conservative treatment failure or clinical reasoning for any injection procedure, since M71.18 is used to support medical necessity under CMS pain management LCDs.
- If bilateral or multi-site infective bursitis is present, evaluate whether M71.19 (multiple sites) is more accurate than M71.18.
Related CPT procedures
Procedure codes commonly billed with M71.18. 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 M71.18 and adjacent codes.
Source · Editorial brief grounded in CDC ICD-10-CM tabular guidance, AAOS coding references, and cited references ↓
- Skipping the B95–/B96– organism code: M71.1 has an explicit 'Use Additional Code' instruction — submitting M71.18 alone is incomplete and audit-prone.
- Using M71.18 when a site-specific M71.1x code exists: if the infected bursa is at the shoulder, elbow, wrist, hand, hip, knee, or ankle/foot, the laterality-specific code is required over this residual code.
- Confusing M71.18 with M71.58 (Other bursitis, not elsewhere classified, other site): M71.18 requires an infectious etiology; M71.58 is for non-infective, non-use-related bursitis at an unlisted site.
- Routing overuse or friction bursitis (e.g., trochanteric, olecranon from repetitive pressure) to M71.18 — those belong under M70.– regardless of secondary infection.
Clinical context
Source · Editorial summary grounded in 5 cited references ↓
M71.18 applies when a patient presents with bursitis caused by an infectious organism at a site that does not map to the named laterality codes in the M71.11–M71.17 range (shoulder, elbow, wrist, hand, hip, knee, ankle/foot). Common anatomical candidates include the ischial bursa, iliopsoas bursa, infrapatellar bursa not classified elsewhere, or any atypical bursal site confirmed by aspiration culture or imaging. The parent code M71.1 carries a mandatory 'Use Additional Code' instruction: always append a B95– (streptococcal/staphylococcal) or B96– (other bacterial) code to identify the causative organism. Failure to do so is an audit flag and may trigger medical necessity denials.
This code falls under MS-DRG v43.0 groups 557 (Tendonitis, myositis and bursitis with MCC) and 558 (without MCC), so comorbidity capture directly affects DRG assignment and facility reimbursement. On the professional side, CMS's pain management LCD (A52863) explicitly lists M71.18 as a supporting medical necessity code for bursal injection procedures.
Do not use M71.18 for bursitis caused by use, overuse, or pressure — those belong under M70.–. Bunion-related bursal inflammation maps to M20.1, not here. Enthesopathies route to M76–M77. If the infective bursitis involves multiple sites simultaneously, use M71.19 instead.
Sibling codes
Other billable codes under M71.1 (laterality / anatomic variants).
Frequently asked questions
Source · Generated from the editorial pipeline, verified against 5 cited references ↓
01When is M71.18 the right code instead of a more specific M71.1x code?
02Do I always need to add an organism code with M71.18?
03What is the difference between M71.18 and M71.58?
04Can M71.18 support a bursal injection claim?
05What DRG does M71.18 map to on the facility side?
06Can I use M71.18 for bursitis caused by repetitive pressure at an unusual site?
07Is M71.18 valid for bilateral infective bursitis at an unlisted site?
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)
- 02icd10data.comhttps://www.icd10data.com/ICD10CM/Codes/M00-M99/M70-M79/M71-/M71.18
- 03cms.govhttps://www.cms.gov/medicare-coverage-database/view/article.aspx?articleId=52863&ver=58
- 04cms.govhttps://www.cms.gov/medicare-coverage-database/view/article.aspx?articleId=60304&ver=3
- 05aapc.comhttps://www.aapc.com/codes/icd-10-codes/M71.18
Mira AI Scribe
Mira AI Scribe captures the specific bursa name, side (if applicable), infectious etiology indicators (aspiration culture, Gram stain, clinical septic presentation), causative organism when identified, and any prior treatment attempted. This detail drives the mandatory B95–/B96– co-code, prevents downcoding to a nonspecific bursitis code, and satisfies CMS medical necessity criteria for associated injection procedures.
See how Mira captures M71.18 documentation