ICD-10 Code H70.10 – Chronic mastoiditis, unspecified ear (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code H70.10 – Chronic mastoiditis, unspecified ear
What it is
H70.10 identifies chronic inflammation or infection of the mastoid air cells behind the ear when the affected side is not specified. Use it when documentation states chronic mastoiditis without laterality.
Clinical signs
Typical findings include persistent ear pain, drainage, or a history of recurrent middle ear infection. Clinical features vary; refer to documentation, and confirm that the provider describes chronic mastoid involvement.
When to use this code
Use H70.10 when the record documents chronic mastoiditis and does not identify the right or left ear. It also fits when the clinician notes mastoid inflammation as an ongoing condition rather than an acute episode. If laterality is available, code it instead.
Do not use for
Do not use this code for acute mastoiditis or for nonspecific ear pain without documented mastoid disease. Check documentation if the note only mentions otitis media, mastoid tenderness, or postoperative changes.
Coding tip
Review the chart for laterality before assigning H70.10, because unspecified ear is appropriate only when the side is not documented.