2026 ICD-10-CM Diagnosis Code S21Open wound of thorax

ICD-10-CM Codes›S00–T88›S20-S29›S21

ICD-10-CM S21
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

S21 is a non-billable ICD-10-CM category code for open wound of thorax, so it cannot be submitted on claims. Use a more specific code from this category instead, such as S21.001A, S21.001D, S21.001S, and S21.002A.

Code Identity

ICD-10-CM Code
S21
Billable Status
No — Non-Billable Category
Code Describes
Open wound of thorax
Chapter
S20-S29
Injuries to the thorax

Code Classification

ChapterS00–T88Injury, poisoning and certain other consequences of external causes
SectionS20-S29Injuries to the thorax
CategoryS21Open wound of thorax
This CodeS21Open wound of thorax

Specific Coding for Open wound of thoraxOverview

Non-specific codes like S21 require more characters. Use one of these billable codes instead:

  • S21.0 for Open wound of breast

  • S21.00 for Unspecified open wound of breast

  • S21.01 for Laceration without foreign body of breast

  • S21.02 for Laceration with foreign body of breast

  • S21.03 for Puncture wound without foreign body of breast

  • S21.04 for Puncture wound with foreign body of breast

  • S21.05 for Open bite of breast

  • S21.1 for Open wound of front wall of thorax without penetration into thoracic cavity

  • S21.10 for Unspecified open wound of front wall of thorax without penetration into thoracic cavity

  • S21.11 for Laceration without foreign body of front wall of thorax without penetration into thoracic cavity

  • S21.12 for Laceration with foreign body of front wall of thorax without penetration into thoracic cavity

  • S21.13 for Puncture wound without foreign body of front wall of thorax without penetration into thoracic cavity

  • S21.14 for Puncture wound with foreign body of front wall of thorax without penetration into thoracic cavity

  • S21.15 for Open bite of front wall of thorax without penetration into thoracic cavity

  • S21.2 for Open wound of back wall of thorax without penetration into thoracic cavity

  • S21.20 for Unspecified open wound of back wall of thorax without penetration into thoracic cavity

  • S21.21 for Laceration without foreign body of back wall of thorax without penetration into thoracic cavity

  • S21.22 for Laceration with foreign body of back wall of thorax without penetration into thoracic cavity

  • S21.23 for Puncture wound without foreign body of back wall of thorax without penetration into thoracic cavity

  • S21.24 for Puncture wound with foreign body of back wall of thorax without penetration into thoracic cavity

  • S21.25 for Open bite of back wall of thorax without penetration into thoracic cavity

  • S21.3 for Open wound of front wall of thorax with penetration into thoracic cavity

  • S21.30 for Unspecified open wound of front wall of thorax with penetration into thoracic cavity

  • S21.31 for Laceration without foreign body of front wall of thorax with penetration into thoracic cavity

  • S21.32 for Laceration with foreign body of front wall of thorax with penetration into thoracic cavity

  • S21.33 for Puncture wound without foreign body of front wall of thorax with penetration into thoracic cavity

  • S21.34 for Puncture wound with foreign body of front wall of thorax with penetration into thoracic cavity

  • S21.35 for Open bite of front wall of thorax with penetration into thoracic cavity

  • S21.4 for Open wound of back wall of thorax with penetration into thoracic cavity

  • S21.40 for Unspecified open wound of back wall of thorax with penetration into thoracic cavity

  • S21.41 for Laceration without foreign body of back wall of thorax with penetration into thoracic cavity

  • S21.42 for Laceration with foreign body of back wall of thorax with penetration into thoracic cavity

  • S21.43 for Puncture wound without foreign body of back wall of thorax with penetration into thoracic cavity

  • S21.44 for Puncture wound with foreign body of back wall of thorax with penetration into thoracic cavity

  • S21.45 for Open bite of back wall of thorax with penetration into thoracic cavity

  • S21.9 for Open wound of unspecified part of thorax

  • S21.90 for Unspecified open wound of unspecified part of thorax

  • S21.91 for Laceration without foreign body of unspecified part of thorax

  • S21.92 for Laceration with foreign body of unspecified part of thorax

  • S21.93 for Puncture wound without foreign body of unspecified part of thorax

  • S21.94 for Puncture wound with foreign body of unspecified part of thorax

  • S21.95 for Open bite of unspecified part of thorax

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.

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Code Also

  • any associated injury, such as:
  • injury of heart S26
  • injury of intrathoracic organs S27
  • rib fracture S22.3 S22.4
  • spinal cord injury S24.0 S24.1
  • traumatic hemopneumothorax S27.3
  • traumatic hemothorax S27.1
  • traumatic pneumothorax S27.0
  • wound infection

Type 1 Excludes

  • traumatic amputation partial of thorax S28.1

7th Character Note

  • The appropriate 7th character is to be added to each code from category S21

7th Character

  • A - initial encounter
  • D - subsequent encounter
  • S - sequela

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.

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 S21Overview

Is S21 (Open wound of thorax) a billable code?

No. This is a category header that groups the codes for open wound of thorax, and headers cannot be submitted on claims. Claims for open wound of thorax need a more specific code from this category, such as S21.001A, S21.001D, and S21.001S.