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ICD-10-CM 2027

ICD-10 code for chronic mastoiditis

H70.1

Chronic mastoiditis

Header — needs a more specific code

From the official ICD-10-CM alphabetic index entry “Mastoiditis (coalescent) (hemorrhagic) (suppurative) › chronic (necrotic) (recurrent)”. Page updated September 29, 2026.

About coding chronic mastoiditis

The ICD-10-CM code for chronic mastoiditis is H70.1 (Chronic mastoiditis).

Within H70 (mastoiditis and related conditions), H70.1 is specifically for chronic mastoiditis. Related codes cover acute mastoiditis (H70.0), petrositis (H70.2), other mastoiditis and related conditions (H70.8) and unspecified mastoiditis (H70.9).

To report this condition, pick the subcode that matches the documentation: H70.10 (unspecified ear), H70.11 (right ear), H70.12 (left ear) and H70.13 (bilateral).

Don't report H70.1 together with the conditions in its Excludes1 note: tuberculous mastoiditis (A18.03).

Don't confuse with (Excludes1 for H70.1)

  • tuberculous mastoiditis (A18.03)

Common questions about chronic mastoiditis ICD-10 codes

What is the ICD-10 code for chronic mastoiditis?

H70.1 — Chronic mastoiditis (a header code; report a more specific subcode).

Is H70.1 billable?

No. H70.1 is a header code. Report one of its more specific subcodes instead.