2026 ICD-10-CM Diagnosis Code T34.539AFrostbite with tissue necrosis of unspecified finger(s), initial encounter

ICD-10-CM Codes›S00–T88›T33-T34›T34

ICD-10-CM T34.539A
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

T34.539A is a billable ICD-10-CM diagnosis code for frostbite with tissue necrosis of unspecified finger(s), 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 922 through 923. The code is flagged as an unspecified code, since codes identifying laterality exist in the same family. Coders also document this condition as frostbite of finger. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Effect of other external causes, initial encounter.

Code Identity

ICD-10-CM Code
T34.539A
Billable Status
Yes — Valid for Submission
Code Describes
Frostbite with tissue necrosis of unspecified finger(s), initial encounter
Short Description
Frostbite w tissue necrosis of unsp finger(s), init encntr
Parent Code
T34.539
Frostbite with tissue necrosis of unspecified finger(s)

Code Classification

ChapterS00–T88Injury, poisoning and certain other consequences of external causes
SectionT33-T34Frostbite
CategoryT34Frostbite with tissue necrosis
This CodeT34.539AFrostbite with tissue necrosis of unspecified finger(s), initial encounter

Code EditsBilling

Medicare Code Editor checks that affect claim validity for T34.539A.

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.

  • Frostbite of finger
  • Frostbite of thumb
  • Tissue necrosis of finger due to and following frostbite
  • Tissue necrosis of hand due to and following frostbite
  • Tissue necrosis of thumb due to and following frostbite

Coding GuidelinesGuidance

The appropriate 7th character is to be added to each code from block Frostbite with tissue necrosis (T34). 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 INJ021
Effect of other external causes, initial encounter
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Frostbite

Frostbite is an injury to the body that is caused by freezing. It most often affects the nose, ears, cheeks, chin, fingers, or toes. Frostbite can permanently damage the body, and severe cases can lead to amputation.

Read the full article at MedlinePlus

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

Convert T34.539A to ICD-9-CMHistory

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

ICD-9-CM
991.1 Frostbite of hand
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 T34.539AOverview

Is T34.539A (Frostbite with tissue necrosis of unspecified finger(s)) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report frostbite with tissue necrosis of unspecified finger(s), initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What does the 7th character A in T34.539A mean?

The final character A marks the initial encounter: use it while the patient is receiving active treatment for frostbite with tissue necrosis of unspecified finger(s), such as an emergency visit or first evaluation.

What MS-DRG does T34.539A group to?

When frostbite with tissue necrosis of unspecified finger(s), initial encounter 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 T34.539A?

Under the General Equivalence Mappings, frostbite with tissue necrosis of unspecified finger(s), initial encounter converts to ICD-9-CM 991.1 (frostbite of hand). 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.