ICD-10 Code H70.891 – Other mastoiditis and related conditions, right ear (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code H70.891 – Other mastoiditis and related conditions, right ear
What it is
This code identifies mastoid inflammation or a related mastoid condition affecting the right ear that is not classified elsewhere. Use it when the documentation specifies the right side and a more specific mastoiditis code does not fit.
Clinical signs
Clinical features vary; refer to documentation. Typical findings may include ear pain, tenderness behind the ear, swelling, redness, or mastoid discomfort, but the record should support a right-ear mastoid process condition.
When to use this code
Use H70.891 when the provider documents other mastoiditis or a related mastoid disorder in the right ear and the diagnosis is not better described by another ICD-10-CM code. This is appropriate for outpatient, inpatient, or specialist notes that clearly identify the right side. If the chart only says “mastoiditis” without laterality, check documentation.
Do not use for
Do not use this code for left or bilateral mastoid disease, or when the condition is better captured by a more specific mastoiditis code. Do not assign it if the documentation is nonspecific; check documentation.
Coding tip
Confirm laterality and the exact mastoid diagnosis in the provider note before coding H70.891.