2026 ICD-10-CM Diagnosis Code S66.921ALaceration of unspecified muscle, fascia and tendon at wrist and hand level, right hand, initial encounter
S66.921A is a billable ICD-10-CM diagnosis code for laceration of unspecified muscle, fascia and tendon at wrist and hand level, right hand, 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. Coders also document this condition as laceration of muscle of right hand. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Open wounds to limbs, initial encounter.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Laceration of muscle of right hand
- Laceration of right wrist
- Laceration of tendon of right hand
- Laceration of tendon of right wrist
- Laceration of tendon of wrist
- Laceration of wrist
Coding GuidelinesGuidance
The appropriate 7th character is to be added to each code from block Injury of muscle, fascia and tendon at wrist and hand level (S66). 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.
Patient EducationClinical
Hand Injuries and Disorders
No matter how old you are or what you do for a living, you are always using your hands. When there is something wrong with them, you may not be able to do your regular activities.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert S66.921A to ICD-9-CMHistory
Code HistoryHistory
Questions About S66.921AOverview
Is S66.921A a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report laceration of unspecified muscle, fascia and tendon at wrist and hand level, right hand, initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What does the 7th character A in S66.921A mean?
The final character A marks the initial encounter: use it while the patient is receiving active treatment for laceration of unspecified muscle, fascia and tendon at wrist and hand level, right hand, such as an emergency visit or first evaluation.
What MS-DRG does S66.921A group to?
When laceration of unspecified muscle, fascia and tendon at wrist and hand level, right hand, 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 S66.921A?
Under the General Equivalence Mappings, laceration of unspecified muscle, fascia and tendon at wrist and hand level, right hand, initial encounter converts to ICD-9-CM 881.22 (opn wound wrist w tendon) and 882.2 (open wound hand 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.
