2027 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 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

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 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 154 through 156, 963 through 965. 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 45 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 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 2027, published by CMS and the National Center for Health Statistics.

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to S09.399A: its own notes plus those printed at S09.3, S09, block S00-S09, and Chapter 19. A note printed at a category, block or chapter applies to every code under it.

Includes

Further defines, or gives examples of, the content of the category.

From Block S00-S09 Injuries to the head applies to 1,934 codes
  • injuries of ear
  • injuries of eye
  • injuries of face [any part]
  • injuries of gum
  • injuries of jaw
  • injuries of oral cavity
  • injuries of palate
  • injuries of periocular area
  • injuries of scalp
  • injuries of temporomandibular joint area
  • injuries of tongue
  • injuries of tooth

Excludes1

Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.

From S09.3 Other specified and unspecified injury of middle and inner ear applies to 30 codes

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 S09.3 Other specified and unspecified injury of middle and inner ear applies to 30 codes
From Block S00-S09 Injuries to the head applies to 1,934 codes
  • burns and corrosions (T20-T32)
  • effects of foreign body in ear (T16)
  • effects of foreign body in larynx (T17.3)
  • effects of foreign body in mouth NOS (T18.0)
  • effects of foreign body in nose (T17.0-T17.1)
  • effects of foreign body in pharynx (T17.2)
  • effects of foreign body on external eye (T15.-)
  • frostbite (T33-T34)
  • insect bite or sting, venomous (T63.4)
From Chapter 19 (S00-T88) Injury, poisoning and certain other consequences of external causes applies to 41,187 codes

Use Additional Code

Add a second code, after this one, to fully describe the condition.

From Chapter 19 (S00-T88) Injury, poisoning and certain other consequences of external causes applies to 41,187 codes
  • code to identify any retained foreign body, if applicable (Z18.-)

Code Also

A second code may be needed to fully describe the condition; the note gives no sequencing direction.

From Block S00-S09 Injuries to the head applies to 1,934 codes
  • for any associated infection

Notes

General instructions on how these codes are used.

From Chapter 19 (S00-T88) Injury, poisoning and certain other consequences of external causes applies to 41,187 codes
  • Use secondary code(s) from Chapter 20, External causes of morbidity, to indicate cause of injury. Codes within the T section that include the external cause do not require an additional external cause code
  • The chapter uses the S-section for coding different types of injuries related to single body regions and the T-section to cover injuries to unspecified body regions as well as poisoning and certain other consequences of external causes.

7th Character

Every code in the category takes a 7th character from the listed values, with the placeholder X filling any empty positions before it.

From S09 Other and unspecified injuries of head applies to 69 codes
  • The appropriate 7th character is to be added to each code from category S09
Values for category S09 Encounter: Initial, Subsequent, Sequela
  • Ainitial encounter this code
  • Dsubsequent encounter
  • Ssequela

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

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

An ear disorder is any condition that changes or harms the shape or structure of your ear. This can include abnormal ear shapes you're born with, injuries that change your ear's shape, and a growth on or in the ear.

The full article covers:

  • What is an ear disorder?
  • What causes ear disorders?
  • What are the symptoms of ear disorders?
  • How are ear disorders diagnosed?
  • How are ear disorders treated?
  • Can ear disorders be prevented?

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 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

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, 2026 through September 30, 2027.

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 156, 964, 965, 155, 154, 963, with relative weights from 0.6656 to 2.6361 depending on complications. Higher weights mean higher Medicare reimbursement.

Is S09.399A a CC or MCC?

CMS lists S09.399A 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 45 closely related codes in its exclusion list.

Can S09.399A be reported with a code from S09.91?

Not as a rule. The Excludes1 note at S09.3, which applies to S09.399A, lists "injury to ear NOS (S09.91-)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).