2026 ICD-10-CM Diagnosis Code S09.90XAUnspecified injury of head, initial encounter

ICD-10-CM Codes›S00–T88›S00-S09›S09

ICD-10-CM S09.90XA
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

S09.90XA is a billable ICD-10-CM diagnosis code for unspecified injury of head, 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 913 through 914, 963 through 965. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other unspecified injury.

Code Identity

ICD-10-CM Code
S09.90XA
Billable Status
Yes — Valid for Submission
Code Describes
Unspecified injury of head, initial encounter
Short Description
Unspecified injury of head, initial encounter
Same as the full description in the CMS dataset.
Parent Code
S09.90
Unspecified injury of head

Code Classification

ChapterS00–T88Injury, poisoning and certain other consequences of external causes
SectionS00-S09Injuries to the head
CategoryS09Other and unspecified injuries of head
This CodeS09.90XAUnspecified injury of head, initial encounter

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Bleeding from nose
  • Chorea due to and following injury of head
  • Chorea due to injury of head
  • Chorea following injury
  • Closed injury of head
  • Closed wound of head
  • Cranial cerebrospinal fluid leak
  • Dystonia due to head injury
  • Friction alopecia
  • Head and neck injury
  • Headache due to injury of head and neck
  • Hemichorea
  • Hemichorea due to head injury
  • Injury of back of head
  • Injury of forehead
  • Injury of head
  • Injury of head and/or neck
  • Injury of head with otorrhagia
  • Injury of head with rhinorrhagia
  • Injury of upper respiratory tract
  • Language disorder associated with thought disorder
  • Leak of cranial cerebrospinal fluid due to and following injury of head
  • Major head injury
  • Metal foreign body in forehead
  • Minor head injury
  • Moderate head injury
  • Multiple injuries of bone of cranium
  • Multiple injuries of head
  • Multiple injuries of head and chest
  • Multiple injuries of thorax
  • Non-accidental injury
  • Non-accidental injury to child
  • Non-accidental traumatic head injury to child
  • Parkinsonism due to and following injury of head
  • Posttraumatic headache
  • Post-traumatic mutism
  • Scalp injury
  • Traumatic alopecia
  • Traumatic epistaxis
  • Vertigo preceded by head injury
  • Wig friction

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 INJ027
Other unspecified injury
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Head Injuries

Chances are you've bumped your head before. Often, the injury is minor because your skull is hard and it protects your brain. But other head injuries can be more severe, such as a skull fracture, concussion, or traumatic brain injury.

Read the full article at MedlinePlus

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

Convert S09.90XA to ICD-9-CMHistory

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

ICD-9-CM
873.8 Open wound of head NEC
Approximate The match is approximate rather than exact.
ICD-9-CM
873.9 Open wnd head NEC-compl
Approximate The match is approximate rather than exact.
ICD-9-CM
959.01 Head injury NOS
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 S09.90XAOverview

Is S09.90XA (Unspecified injury of head) a billable code?

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

What does the 7th character A in S09.90XA mean?

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

What MS-DRG does S09.90XA group to?

When unspecified injury of head, initial encounter is the principal diagnosis on an inpatient stay, it groups to MS-DRG 913, 914, 963, 964, 965, with relative weights from 0.8855 to 2.7338 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of S09.90XA?

Under the General Equivalence Mappings, unspecified injury of head, initial encounter converts to ICD-9-CM 873.8 (open wound of head NEC), 873.9 (open wnd head NEC-compl), and 959.01 (head injury NOS). 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.