2027 ICD-10-CM Diagnosis Code H70.002Acute mastoiditis without complications, left ear

ICD-10-CM Codes›H60–H95›H65-H75›H70

ICD-10-CM H70.002
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

H70.002 is a billable ICD-10-CM diagnosis code for acute mastoiditis without complications, left 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. Coders also document this condition as acute left mastoiditis. 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
H70.002
Billable Status
Yes — Valid for Submission
Code Describes
Acute mastoiditis without complications, left ear
Short Description
Acute mastoiditis without complications, left 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 CodeH70.002Acute mastoiditis without complications, left ear

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Acute left mastoiditis
  • Acute mastoiditis
  • Left mastoiditis

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to H70.002: 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 H70.002, its category, or a range that includes it.

Excludes2 1

These codes carry an Excludes2 note naming H70.002: 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 H70.002 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 H70.002Overview

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

The ICD-10-CM code for acute mastoiditis without complications, left ear is H70.002 (sometimes written as H70002). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is H70.002 (Acute mastoiditis without complications) a billable code?

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

What MS-DRG does H70.002 group to?

When acute mastoiditis without complications, left 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 H70.002 a CC or MCC?

CMS lists H70.002 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 H70.002?

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