2026 ICD-10-CM Diagnosis Code S46.329ALaceration of muscle, fascia and tendon of triceps, unspecified arm, initial encounter

ICD-10-CM Codes›S00–T88›S40-S49›S46

ICD-10-CM S46.329A
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

S46.329A is a billable ICD-10-CM diagnosis code for laceration of muscle, fascia and tendon of triceps, unspecified arm, 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 564 through 566, 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 injury of fascia of triceps brachii. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Open wounds to limbs, initial encounter.

Code Identity

ICD-10-CM Code
S46.329A
Billable Status
Yes — Valid for Submission
Code Describes
Laceration of muscle, fascia and tendon of triceps, unspecified arm, initial encounter
Short Description
Laceration of musc/fasc/tend triceps, unsp arm, init
Parent Code
S46.329
Laceration of muscle, fascia and tendon of triceps, unspecified arm

Code Classification

ChapterS00–T88Injury, poisoning and certain other consequences of external causes
SectionS40-S49Injuries to the shoulder and upper arm
CategoryS46Injury of muscle, fascia and tendon at shoulder and upper arm level
This CodeS46.329ALaceration of muscle, fascia and tendon of triceps, unspecified arm, initial encounter

Code EditsBilling

Medicare Code Editor checks that affect claim validity for S46.329A.

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.

  • Injury of fascia of triceps brachii
  • Injury of triceps brachii muscle
  • Laceration of fascia of triceps brachii
  • Laceration of tendon of triceps brachii
  • Laceration of triceps brachii

Coding GuidelinesGuidance

The appropriate 7th character is to be added to each code from block Injury of muscle, fascia and tendon at shoulder and upper arm level (S46). 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 INJ012
Open wounds to limbs, initial encounter
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Arm Injuries and Disorders

Of the 206 bones in your body, three of them are in your arm: the humerus, radius, and ulna. Your arms are also made up of muscles, joints, tendons, and other connective tissue. Injuries to any of these parts of the arm can occur during sports, a fall, or an accident.

Read the full article at MedlinePlus

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

Convert S46.329A to ICD-9-CMHistory

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

ICD-9-CM
880.20 Opn wnd shouldr w tendon
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 S46.329AOverview

Is S46.329A a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report laceration of muscle, fascia and tendon of triceps, unspecified arm, initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What does the 7th character A in S46.329A mean?

The final character A marks the initial encounter: use it while the patient is receiving active treatment for laceration of muscle, fascia and tendon of triceps, unspecified arm, such as an emergency visit or first evaluation.

What MS-DRG does S46.329A group to?

When laceration of muscle, fascia and tendon of triceps, unspecified arm, initial encounter is the principal diagnosis on an inpatient stay, it groups to MS-DRG 564, 565, 566, 963, 964, 965, with relative weights from 0.7493 to 2.7338 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of S46.329A?

Under the General Equivalence Mappings, laceration of muscle, fascia and tendon of triceps, unspecified arm, initial encounter converts to ICD-9-CM 880.20 (opn wnd shouldr w tendon). 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.