ICD-10 Code H70.9 – Unspecified mastoiditis (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code H70.9 – Unspecified mastoiditis
What it is
H70.9 identifies mastoiditis when the mastoid infection or inflammation is documented, but the provider does not specify the type or laterality. Use it for a general mastoiditis diagnosis without further detail.
Clinical signs
Typical findings include ear pain, fever, postauricular tenderness, swelling, or redness, but clinical features vary; refer to documentation. Imaging or exam may support mastoid involvement.
When to use this code
Use H70.9 when the record states mastoiditis and no more specific code is available. It also fits when the note lacks detail on acute, chronic, or other specified mastoiditis.
If laterality or a more specific type is documented elsewhere, code that instead. Check documentation carefully before defaulting to unspecified.
Do not use for
Do not use this code for otitis media without mastoid involvement, or for a specified mastoiditis subtype when the documentation supports a more precise code.
Coding tip
Query the provider if the chart says mastoiditis but does not clarify type, laterality, or acuity.