ICD-10 Code H70.09 – Acute mastoiditis with other complications (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code H70.09 – Acute mastoiditis with other complications
What it is
H70.09 identifies acute mastoiditis, an infection of the mastoid air cells behind the ear, when the record documents complications other than those named in more specific codes. Use the code when the complication is acute and clearly linked to mastoiditis.
Clinical signs
Typical findings include ear pain, fever, tenderness or swelling behind the ear, and signs of middle ear infection. Clinical features vary; refer to documentation for the specific complication, such as abscess or spread beyond the mastoid.
When to use this code
Use H70.09 when the provider documents acute mastoiditis with an additional complication that is not separately named in a more specific ICD-10 code. It may apply when the note clearly states a complication, but the exact type is not otherwise indexed. Check documentation if the complication is vague or incomplete.
Do not use for
Do not use this code for uncomplicated acute mastoiditis or for chronic mastoiditis. Also avoid it when a more specific mastoiditis code matches the documented complication.
Coding tip
Code the complication only if the documentation clearly links it to acute mastoiditis and no more specific code applies.