ICD-10-CM 2027
ICD-10 code for mastoiditis
From the official ICD-10-CM alphabetic index entry “Mastoiditis (coalescent) (hemorrhagic) (suppurative)”. Page updated September 29, 2026.
About coding mastoiditis
The ICD-10-CM code for mastoiditis is H70.9 (Unspecified mastoiditis). The official index lists 9 more specific codes, so check the documentation for details such as type, cause, site or severity before settling on H70.9.
Within H70, choose H70.9 (Unspecified mastoiditis) only when documentation doesn't support a more specific option: acute mastoiditis (H70.0), chronic mastoiditis (H70.1), petrositis (H70.2) and other mastoiditis and related conditions (H70.8).
To report this condition, pick the subcode that matches the documentation: H70.90 (unspecified ear), H70.91 (right ear), H70.92 (left ear) and H70.93 (bilateral).
It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.
More specific mastoiditis codes (official index)
- acute, subacute H70.00 — Acute mastoiditis without complications
- complicated NEC H70.09 — Acute mastoiditis with other complications
- subperiosteal H70.01 — Subperiosteal abscess of mastoid
- chronic (necrotic) (recurrent) H70.1 — Chronic mastoiditis
- in (due to)
- infectious disease NEC B99 — Other and unspecified infectious diseases
- parasitic disease NEC B89 — Unspecified parasitic disease
- tuberculosis A18.03 — Tuberculosis of other bones
- petrositis
- postauricular fistula
- specified NEC H70.89 — Other mastoiditis and related conditions
- tuberculous A18.03 — Tuberculosis of other bones
Common questions about mastoiditis ICD-10 codes
What is the ICD-10 code for mastoiditis?
- H70.9 — Unspecified mastoiditis (a header code; report a more specific subcode). More specific codes apply when the documentation supports them: H70.00, H70.09, H70.01, H70.1 and others below.
What is the ICD-10 code for chronic mastoiditis?
- H70.1 — Chronic mastoiditis (header code; choose a more specific subcode).
What is the ICD-10 code for tuberculous mastoiditis?
- A18.03 — Tuberculosis of other bones.
Is H70.9 billable?
- No. H70.9 is a header code. Report one of its more specific subcodes instead.