Infective inflammation of a tendon sheath or synovial membrane caused by a pathogen other than gonococci or tuberculosis, documented without specification of the anatomical site.
Verified May 8, 2026 · 5 sources ↓
- Status
- Billable
- Chapter
- 13
- Related CPT
- 7
- Region
- General
Documentation tips
What should appear in the chart to support M65.10.
Source · Editorial brief grounded in 5 cited references ↓
- Record the specific anatomical site and side (right vs. left) in every encounter note — even 'right wrist' unlocks a more specific child code and avoids M65.10.
- Document clinical signs supporting infection: Kanavel's cardinal signs for flexor sheaths, purulent drainage, fever, or elevated WBC/CRP/ESR.
- Capture culture and sensitivity results or the suspected organism so a B95–B97 causative organism code can be added alongside M65.10.
- Distinguish infective tenosynovitis (M65.1x) from non-infective/inflammatory tenosynovitis (M65.8x) explicitly in the assessment — payers treat them differently.
- Note any prior antibiotic treatment or failed conservative care, which supports medical necessity for surgical drainage or irrigation procedures.
Related CPT procedures
Procedure codes commonly billed with M65.10. 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 M65.10 and adjacent codes.
Source · Editorial brief grounded in CDC ICD-10-CM tabular guidance, AAOS coding references, and cited references ↓
- Defaulting to M65.10 when a site is documented in the note — always assign the site-specific child code (M65.11–M65.17) when laterality or region appears anywhere in the record.
- Omitting the causative organism code (B95–B97) when culture results or clinical diagnosis name the pathogen — payers may deny or request additional documentation.
- Confusing M65.10 with M65.9 (unspecified synovitis/tenosynovitis, unspecified site) — M65.9 is non-infective; use M65.10 only when infection is confirmed or clinically established.
- Coding M65.10 for use-related or overuse tenosynovitis — those belong under M70.– and are Excludes1 to the M65 category.
- Assigning M65.10 for gonococcal tenosynovitis (A54.42) or tuberculous tenosynovitis (A18.09) — both are excluded from M65.1 by classification rules.
Clinical context
Source · Editorial summary grounded in 5 cited references ↓
M65.10 covers bacterial, fungal, or other non-gonococcal, non-tuberculous infectious tenosynovitis when the treating provider has not documented which joint or tendon region is affected. It sits under parent code M65.1 (Other infective (teno)synovitis), which branches into site-specific and laterality-specific child codes for shoulder, elbow, wrist, hand, hip, knee, ankle, and foot.
Use M65.10 only when site documentation is genuinely absent from the record. If the provider documents even a general region — 'right wrist,' 'left ankle,' 'hand' — drop to the appropriate site-specific code (e.g., M65.131 for right wrist, M65.172 for left ankle and foot). Defaulting to M65.10 when a site is documented is a specificity failure that invites payer downcoding or audit flags.
When infection is confirmed, pair M65.10 with a causative organism code from B95–B97 (e.g., B95.6 for Staphylococcus aureus). The M65 category carries an Excludes1 for chronic crepitant synovitis of hand and wrist (M70.0–), current injuries (code to the injury by body region), and soft tissue disorders related to use/overuse/pressure (M70.–) — none of those can be coded alongside M65.10 for the same condition.
Sibling codes
Other billable codes under M65.1 (laterality / anatomic variants).
Frequently asked questions
Source · Generated from the editorial pipeline, verified against 5 cited references ↓
01When is M65.10 the correct code rather than a site-specific M65.1x code?
02Do I need a second code for the causative organism?
03Can M65.10 and M70.– codes be used together for the same encounter?
04What distinguishes M65.10 from M65.9?
05Is M65.10 valid for gonococcal or tuberculous tenosynovitis?
06How does M65.10 interact with surgical drainage CPT codes?
07Can M65.10 be used for fungal tenosynovitis?
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/M65-M67/M65-/M65.10
- 03aapc.comhttps://www.aapc.com/codes/icd-10-codes/M65.10
- 04icdcodes.aihttps://icdcodes.ai/diagnosis/flexor-tenosynovitis/documentation
- 05cms.govhttps://www.cms.gov/medicare/coordination-benefits-recovery/overview/icd-code-lists
Mira AI Scribe
Mira's AI scribe captures the affected tendon sheath region and side, clinical infection markers (Kanavel's signs, purulent drainage, lab values), and the identified or suspected organism from the encounter note. That documentation drives assignment of the most specific M65.1x child code plus the correct B95–B97 organism code — preventing a fallback to M65.10 and the audit exposure that comes with unspecified-site coding when site information exists in the record.
See how Mira captures M65.10 documentation