2026 ICD-10-CM Diagnosis Code S46.121ALaceration of muscle, fascia and tendon of long head of biceps, right arm, initial encounter

ICD-10-CM Codes›S00–T88›S40-S49›S46

ICD-10-CM S46.121A
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

S46.121A is a billable ICD-10-CM diagnosis code for laceration of muscle, fascia and tendon of long head of biceps, right 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. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Open wounds to limbs, initial encounter.

Code Identity

ICD-10-CM Code
S46.121A
Billable Status
Yes — Valid for Submission
Code Describes
Laceration of muscle, fascia and tendon of long head of biceps, right arm, initial encounter
Short Description
Laceration of musc/fasc/tend long hd bicep, right arm, init
Parent Code
S46.121
Laceration of muscle, fascia and tendon of long head of biceps, right 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 CodeS46.121ALaceration of muscle, fascia and tendon of long head of biceps, right arm, initial encounter

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Injury of muscle of long head of biceps
  • Injury of muscle of right upper arm
  • Injury of tendon of long head of right biceps brachii
  • Laceration of biceps brachii
  • Laceration of muscle of long head of biceps brachii
  • Laceration of muscle of long head of right biceps brachii
  • Laceration of muscle of right upper arm
  • Laceration of right biceps brachii muscle
  • Laceration of right shoulder
  • Laceration of right upper arm
  • Laceration of tendon of biceps brachii
  • Laceration of tendon of long head of biceps brachii
  • Laceration of tendon of long head of right biceps brachii
  • Laceration of tendon of right biceps brachii
  • Laceration of tendon of right upper arm
  • Laceration of tendon of upper arm
  • Right biceps brachii muscle traumatic injury

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

Shoulder Injuries and Disorders

Your shoulder joint is composed of three bones: the clavicle (collarbone), the scapula (shoulder blade), and the humerus (upper arm bone). Your shoulders are the most movable joints in your body. They can also be unstable because the ball of the upper arm is larger than the shoulder socket that holds it.

Read the full article at MedlinePlus

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

Convert S46.121A 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 S46.121AOverview

Is S46.121A a billable code?

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

What does the 7th character A in S46.121A 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 long head of biceps, right arm, such as an emergency visit or first evaluation.

What MS-DRG does S46.121A group to?

When laceration of muscle, fascia and tendon of long head of biceps, right 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 S46.121A?

Under the General Equivalence Mappings, laceration of muscle, fascia and tendon of long head of biceps, right 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.