2026 ICD-10-CM Diagnosis Code Z04.1Encounter for examination and observation following transport accident

ICD-10-CM Codes›Z00–Z99›Z00-Z13›Z04

ICD-10-CM Z04.1
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

Z04.1 is a billable ICD-10-CM diagnosis code for encounter for examination and observation following transport accident. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 922 through 923. Coders also document this condition as accident - pressure in aircraft. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Encounter for observation and examination for conditions ruled out (excludes infectious disease, neoplasm, mental disorders).

Code Identity

ICD-10-CM Code
Z04.1
Billable Status
Yes — Valid for Submission
Code Describes
Encounter for examination and observation following transport accident
Short Description
Encounter for exam and obs following transport accident
Parent Code
Z04
Encounter for examination and observation for other reasons

Code Classification

ChapterZ00–Z99Factors influencing health status and contact with health services
SectionZ00-Z13Persons encountering health services for examinations
CategoryZ04Encounter for examination and observation for other reasons
This CodeZ04.1Encounter for examination and observation following transport accident

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Accident - pressure in aircraft
  • Accident due to sudden change in air pressure in aircraft

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Type 1 Excludes

  • encounter for examination and observation following work accident Z04.2

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Examination(for) (following) (general) (of) (routine)
      • following
        • accident NEC
          • transport
    • Examination(for) (following) (general) (of) (routine)
      • following
        • motor vehicle accident
    • Observation(following) (for) (without need for further medical care)
      • accident NEC
        • transport

Clinical ClassificationClinical

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

CCSR FAC003
Encounter for observation and examination for conditions ruled out (excludes infectious disease, neoplasm, mental disorders)
Default principal diagnosis: inpatient Yes · outpatient Yes

Convert Z04.1 to ICD-9-CMHistory

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

ICD-9-CM
V71.4 Observ-accident NEC
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 Z04.1Overview

Is Z04.1 (Encounter for examination and observation for other reasons) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report encounter for examination and observation following transport accident on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does Z04.1 group to?

When encounter for examination and observation following transport accident is the principal diagnosis on an inpatient stay, it groups to MS-DRG 922, 923, with relative weights from 1.0177 to 1.7494 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of Z04.1?

Under the General Equivalence Mappings, encounter for examination and observation following transport accident converts to ICD-9-CM V71.4 (observ-accident NEC). The mapping is approximate, so confirm the match fits the documentation.