2027 ICD-10-CM Diagnosis Code H70.009Acute mastoiditis without complications, unspecified ear

ICD-10-CM Codes›H60–H95›H65-H75›H70

ICD-10-CM H70.009
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

H70.009 is a billable ICD-10-CM diagnosis code for acute mastoiditis without complications, unspecified ear. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 152 through 153. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 76 closely related codes. The code is flagged as an unspecified code, since codes identifying laterality exist in the same family. Coders also document this condition as abscess of mastoid. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Diseases of middle ear and mastoid (except otitis media).

Code Identity

ICD-10-CM Code
H70.009
Billable Status
Yes — Valid for Submission
Code Describes
Acute mastoiditis without complications, unspecified ear
Short Description
Acute mastoiditis without complications, unspecified ear
Same as the full description in the CMS dataset.
Parent Code
H70.00
Acute mastoiditis without complications

Code Classification

ChapterH60–H95Diseases of the ear and mastoid process
SectionH65-H75Diseases of middle ear and mastoid
CategoryH70Mastoiditis and related conditions
This CodeH70.009Acute mastoiditis without complications, unspecified ear

Code EditsBilling

Medicare Code Editor checks that affect claim validity for H70.009.

Unspecified codes
Unspecified codes exist in the ICD-10-CM classification for circumstances when documentation in the medical record does not provide the level of detail needed to support reporting a more specific code. However, in the inpatient setting, there should generally be very limited and rare circumstances for which the laterality (right, left, bilateral) of a condition is unable to be documented and reported. The following pages contain the list of unspecified ICD-10-CM diagnosis codes for which there is a more specific code to identify laterality (right, left, bilateral) within that code family.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Abscess of mastoid
  • Abscess of temporal bone
  • Acute mastoiditis
  • Acute suppurative mastoiditis
  • Empyema of mastoid

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to H70.009: its own notes plus those printed at Chapter 8. A note printed at a category, block or chapter applies to every code under it.

Excludes2

Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.

From Chapter 8 (H60-H95) Diseases of the ear and mastoid process applies to 653 codes
  • certain conditions originating in the perinatal period (P04-P96)
  • certain infectious and parasitic diseases (A00-B99)
  • complications of pregnancy, childbirth and the puerperium (O00-O9A)
  • congenital malformations, deformations and chromosomal abnormalities (Q00-Q99)
  • endocrine, nutritional and metabolic diseases (E00-E88)
  • injury, poisoning and certain other consequences of external causes (S00-T88)
  • neoplasms (C00-D49)
  • symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)

Notes

General instructions on how these codes are used.

From Chapter 8 (H60-H95) Diseases of the ear and mastoid process applies to 653 codes
  • Use an external cause code following the code for the ear condition, if applicable, to identify the cause of the ear condition

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name H70.009, its category, or a range that includes it.

Excludes2 1

These codes carry an Excludes2 note naming H70.009: its condition is not part of those codes, and both may be reported when the patient has both.

  • H74 Other disorders of middle ear mastoid
    mastoiditis (H70.-) names H70.-, which includes this code

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR EAR002
Diseases of middle ear and mastoid (except otitis media)
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Ear Infections

Ear infections are the most common reason parents bring their child to a doctor. Three out of four children will have at least one ear infection by their third birthday. Adults can also get ear infections, but they are less common.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert H70.009 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
383.00 Ac mastoiditis w/o compl
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About H70.009Overview

What is the ICD-10 code for acute mastoiditis without complications, unspecified ear?

The ICD-10-CM code for acute mastoiditis without complications, unspecified ear is H70.009 (sometimes written as H70009). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is H70.009 (Acute mastoiditis without complications) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report acute mastoiditis without complications, unspecified ear on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does H70.009 group to?

When acute mastoiditis without complications, unspecified ear is the principal diagnosis on an inpatient stay, it groups to MS-DRG 152, 153, with relative weights from 0.7420 to 1.1147 depending on complications. Higher weights mean higher Medicare reimbursement.

Is H70.009 a CC or MCC?

CMS lists H70.009 as a CC (complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 76 closely related codes in its exclusion list.

What is the ICD-9 equivalent of H70.009?

Under the General Equivalence Mappings, acute mastoiditis without complications, unspecified ear converts to ICD-9-CM 383.00 (ac mastoiditis w/o compl). The mapping is approximate, so confirm the match fits the documentation.