H70.12 Chronic mastoiditis, left ear

Billable ICD-10-CM code, FY2026.

Applies from H70.1 Chronic mastoiditis

Applicable to

• Caries of mastoid
• Fistula of mastoid

Excludes1 (never code together)

• tuberculous mastoiditis (A18.03)

MS-DRG index

Defines the logic of DRG(s) 152-153 in MDC 03.

Approximate ICD-9-CM (GEMs)

• 383.1 Chronic mastoiditis (approximate)

Code annotations containing back-references to H70.12

Back-references to H70

• Type 2 Excludes: H74 Other disorders of middle ear mastoid ("mastoiditis (H70.-)")

Nearby codes

• H70.093 Acute mastoiditis with other complications, bilateral
• H70.099 Acute mastoiditis with other complications, unspecified ear
• H70.1 Chronic mastoiditis
• H70.10 Chronic mastoiditis, unspecified ear
• H70.11 Chronic mastoiditis, right ear
• H70.12 Chronic mastoiditis, left ear (this code)
• H70.13 Chronic mastoiditis, bilateral
• H70.2 Petrositis
• H70.20 Unspecified petrositis
• H70.201 Unspecified petrositis, right ear
• H70.202 Unspecified petrositis, left ear