ICD-10 Code H70.013 – Subperiosteal abscess of mastoid, bilateral (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code H70.013 – Subperiosteal abscess of mastoid, bilateral
What it is
This code identifies a bilateral subperiosteal abscess of the mastoid, meaning pus has collected beneath the periosteum over both mastoid bones. It reflects a serious complication of mastoid infection.
Clinical signs
Typical findings include postauricular swelling, tenderness, erythema, and ear displacement. Clinical features vary; refer to documentation and imaging when recorded.
When to use this code
Use H70.013 when the provider documents a subperiosteal abscess involving both mastoid areas. Code it from the diagnosis, operative note, or imaging report when the bilateral site is clearly stated. If laterality is not documented, check documentation before assigning this code.
Do not use for
Do not use this code for uncomplicated mastoiditis without abscess formation. Do not assign it when only one side is documented or when the record is unclear.
Coding tip
Verify bilateral involvement in the final provider documentation before coding H70.013.