ICD-10 Code H70.009 – Acute mastoiditis without complications, unspecified ear (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code H70.009 – Acute mastoiditis without complications, unspecified ear
What it is
This code identifies an acute infection and inflammation of the mastoid air cells behind the ear, without documented complications. Use it when the record does not specify the right or left ear.
Clinical signs
Typical findings include ear pain, fever, swelling or tenderness behind the ear, and a protruding pinna. Clinical features vary; refer to documentation for the ear involved and whether complications are present.
When to use this code
Use H70.009 when the provider documents acute mastoiditis, no complications, and does not identify the affected ear. It is appropriate for confirmed cases in which the chart lacks laterality or says “unspecified ear.”
If the note mentions abscess, intracranial spread, or another complication, this code is not correct. You should code only what is documented and supported in the assessment.
Do not use for
Do not use this code for chronic mastoiditis, mastoiditis with complications, or cases where the ear is clearly documented as right or left. Check documentation.
Coding tip
Confirm both acuity and laterality in the provider note before assigning H70.009.