2027 ICD-10-CM Diagnosis Code S29.012AStrain of muscle and tendon of back wall of thorax, initial encounter
S29.012A is a billable ICD-10-CM diagnosis code for strain of muscle and tendon of back wall of thorax, 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 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 562 through 563, 963 through 965. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Sprains and strains, initial encounter.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Left shoulder skeletal muscle injury
- Right shoulder skeletal muscle injury
- Rupture of left trapezius muscle
- Rupture of right trapezius muscle
- Rupture of trapezius muscle
- Strain of left rhomboid muscle
- Strain of left trapezius muscle
- Strain of muscle of chest wall
- Strain of muscle of left shoulder
- Strain of muscle of right shoulder
- Strain of neck muscle
- Strain of right rhomboid muscle
- Strain of right trapezius muscle
- Strain of trapezius muscle
Coding GuidelinesGuidance
The appropriate 7th character is to be added to each code from block Other and unspecified injuries of thorax (S29). 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 2027, published by CMS and the National Center for Health Statistics.
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to S29.012A: its own notes plus those printed at S29, block S20-S29, and Chapter 19. A note printed at a category, block or chapter applies to every code under it.
Includes
Further defines, or gives examples of, the content of the category.
- injuries of breast
- injuries of chest (wall)
- injuries of interscapular area
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.
- burns and corrosions (T20-T32)
- effects of foreign body in bronchus (T17.5)
- effects of foreign body in esophagus (T18.1)
- effects of foreign body in lung (T17.8)
- effects of foreign body in trachea (T17.4)
- frostbite (T33-T34)
- injuries of axilla
- injuries of clavicle
- injuries of scapular region
- injuries of shoulder
- insect bite or sting, venomous (T63.4)
Use Additional Code
Add a second code, after this one, to fully describe the condition.
- code to identify any retained foreign body, if applicable (Z18.-)
Code Also
A second code may be needed to fully describe the condition; the note gives no sequencing direction.
Notes
General instructions on how these codes are used.
- Use secondary code(s) from Chapter 20, External causes of morbidity, to indicate cause of injury. Codes within the T section that include the external cause do not require an additional external cause code
- The chapter uses the S-section for coding different types of injuries related to single body regions and the T-section to cover injuries to unspecified body regions as well as poisoning and certain other consequences of external causes.
7th Character
Every code in the category takes a 7th character from the listed values, with the placeholder X filling any empty positions before it.
- The appropriate 7th character is to be added to each code from category S29
- Ainitial encounter this code
- Dsubsequent encounter
- Ssequela
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name S29.012A, its category, or a range that includes it.
Excludes2 1
These codes carry an Excludes2 note naming S29.012A: its condition is not part of those codes, and both may be reported when the patient has both.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Chest Injuries and Disorders
The chest is the part of your body between your neck and your abdomen (belly). The medical term for your chest is thorax.
The full article covers:
- What is the chest?
- What are chest injuries and disorders?
- How are chest injuries and disorders diagnosed?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert S29.012A to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About S29.012AOverview
What is the ICD-10 code for strain of muscle and tendon of back wall of thorax, initial encounter?
The ICD-10-CM code for strain of muscle and tendon of back wall of thorax, initial encounter is S29.012A (sometimes written as S29012A). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is S29.012A (Strain of muscle and tendon of back wall of thorax) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report strain of muscle and tendon of back wall of thorax, initial encounter on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What does the 7th character A in S29.012A mean?
The final character A marks the initial encounter: use it while the patient is receiving active treatment for strain of muscle and tendon of back wall of thorax, such as an emergency visit or first evaluation.
What MS-DRG does S29.012A group to?
When strain of muscle and tendon of back wall of thorax, initial encounter is the principal diagnosis on an inpatient stay, it groups to MS-DRG 563, 964, 965, 562, 963, with relative weights from 0.8982 to 2.6361 depending on complications. Higher weights mean higher Medicare reimbursement.
What is the ICD-9 equivalent of S29.012A?
Under the General Equivalence Mappings, strain of muscle and tendon of back wall of thorax, initial encounter converts to ICD-9-CM 848.8 (sprain NEC). The mapping is approximate, so confirm the match fits the documentation.
