2026 ICD-10-CM Diagnosis Code S09.399AOther specified injury of unspecified middle and inner ear, initial encounter

ICD-10-CM Codes›S00–T88›S00-S09›S09

ICD-10-CM S09.399A
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

S09.399A is a billable ICD-10-CM diagnosis code for other specified injury of unspecified middle and inner ear, initial encounter. The 7th character A marks it as an initial encounter code, used while the patient is receiving active treatment. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 154 through 156, 963 through 965. The code is flagged as an unspecified code, since codes identifying laterality exist in the same family. Coders also document this condition as cochlear trauma. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified injury.

Code Identity

ICD-10-CM Code
S09.399A
Billable Status
Yes — Valid for Submission
Code Describes
Other specified injury of unspecified middle and inner ear, initial encounter
Short Description
Oth injury of unspecified middle and inner ear, init encntr
Parent Code
S09.399
Other specified injury of unspecified middle and inner ear

Code Classification

ChapterS00–T88Injury, poisoning and certain other consequences of external causes
SectionS00-S09Injuries to the head
CategoryS09Other and unspecified injuries of head
This CodeS09.399AOther specified injury of unspecified middle and inner ear, initial encounter

Code EditsBilling

Medicare Code Editor checks that affect claim validity for S09.399A.

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.

  • Cochlear trauma
  • Concussive cochlear trauma
  • Dislocation of ear ossicles
  • Labyrinthine concussion
  • Traumatic ossicular dislocation
  • Vestibular trauma

Coding GuidelinesGuidance

The appropriate 7th character is to be added to each code from block Other and unspecified injuries of head (S09). Use the following options for the applicable episode of care:

  • A - initial encounter
  • D - subsequent encounter
  • S - sequela

Source: ICD-10-CM Official Guidelines for Coding and Reporting, FY 2026, published by CMS and the National Center for Health Statistics.

Clinical ClassificationClinical

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

CCSR INJ026
Other specified injury
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Ear Disorders

Your ear has three main parts: outer, middle and inner. You use all of them in hearing. Sound waves come in through your outer ear. They reach your middle ear, where they make your eardrum vibrate. The vibrations are transmitted through three tiny bones, called ossicles, in your middle ear.

Read the full article at MedlinePlus

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

Convert S09.399A to ICD-9-CMHistory

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

ICD-9-CM
872.62 Open wound of ossicles
Approximate The match is approximate rather than exact.
ICD-9-CM
872.63 Open wnd eustachian tube
Approximate The match is approximate rather than exact.
ICD-9-CM
872.64 Open wound of cochlea
Approximate The match is approximate rather than exact.
ICD-9-CM
872.69 Open wound of ear NEC
Approximate The match is approximate rather than exact.
ICD-9-CM
872.72 Open wnd ossicles-compl
Approximate The match is approximate rather than exact.
ICD-9-CM
872.73 Opn wnd eustach tb-compl
Approximate The match is approximate rather than exact.
ICD-9-CM
872.74 Open wound cochlea-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 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About S09.399AOverview

Is S09.399A (Other specified injury of unspecified middle and inner ear) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report other specified injury of unspecified middle and inner ear, initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What does the 7th character A in S09.399A mean?

The final character A marks the initial encounter: use it while the patient is receiving active treatment for other specified injury of unspecified middle and inner ear, such as an emergency visit or first evaluation.

What MS-DRG does S09.399A group to?

When other specified injury of unspecified middle and inner ear, initial encounter is the principal diagnosis on an inpatient stay, it groups to MS-DRG 154, 155, 156, 963, 964, 965, with relative weights from 0.6911 to 2.7338 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of S09.399A?

Under the General Equivalence Mappings, other specified injury of unspecified middle and inner ear, initial encounter converts to ICD-9-CM 872.62 (open wound of ossicles), 872.63 (open wnd eustachian tube), and 872.64 (open wound of cochlea). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.