ICD-10 Code H75.03 – Mastoiditis in Infectious and Parasitic Diseases Classified Elsewhere, Bilateral (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code H75.03 – Mastoiditis in infectious and parasitic diseases classified elsewhere, bilateral
What it is
This code identifies bilateral mastoiditis when the ear infection is due to an infectious or parasitic disease classified elsewhere. Use it when the mastoid process is involved on both sides and the underlying cause is documented separately.
Clinical signs
Typical findings include ear pain, tenderness behind both ears, swelling, and possible otorrhea. Clinical features vary; refer to documentation for evidence of bilateral mastoid involvement and the associated underlying infection.
When to use this code
Use H75.03 when the record clearly states bilateral mastoiditis and links it to an infectious or parasitic disease coded elsewhere. You should also code the underlying condition separately, following the provider’s documentation and sequencing rules.
Choose this code only when both mastoids are affected. If the note describes mastoiditis without laterality, or does not identify an infectious or parasitic cause, check documentation before assigning H75.03.
Do not use for
Do not use this code for unilateral mastoiditis, nonspecific mastoiditis, or cases where the underlying disease is not documented. Check documentation if the chart does not clearly support bilateral disease.
Coding tip
Code the external cause only if documented, and always pair H75.03 with the separate code for the underlying infection.