2026 ICD-10-CM Diagnosis Code S21.342APuncture wound with foreign body of left front wall of thorax with penetration into thoracic cavity, initial encounter
S21.342A is a billable ICD-10-CM diagnosis code for puncture wound with foreign body of left front wall of thorax with penetration into thoracic cavity, 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 913 through 914, 963 through 965. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Open wounds of trunk, initial encounter.
Code Identity
Code Classification
Coding GuidelinesGuidance
The appropriate 7th character is to be added to each code from block Open wound of thorax (S21). 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
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 S21.342A to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About S21.342AOverview
Is S21.342A a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report puncture wound with foreign body of left front wall of thorax with penetration into thoracic cavity, initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What does the 7th character A in S21.342A mean?
The final character A marks the initial encounter: use it while the patient is receiving active treatment for puncture wound with foreign body of left front wall of thorax with penetration into thoracic cavity, such as an emergency visit or first evaluation.
What MS-DRG does S21.342A group to?
When puncture wound with foreign body of left front wall of thorax with penetration into thoracic cavity, initial encounter is the principal diagnosis on an inpatient stay, it groups to MS-DRG 913, 914, 963, 964, 965, with relative weights from 0.8855 to 2.7338 depending on complications. Higher weights mean higher Medicare reimbursement.
What is the ICD-9 equivalent of S21.342A?
Under the General Equivalence Mappings, puncture wound with foreign body of left front wall of thorax with penetration into thoracic cavity, initial encounter converts to ICD-9-CM 862.9 (intrathorac inj NOS-open). 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.
