2027 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 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

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
Short Description
Open wound of thorax
Same as the full description in the CMS dataset.
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 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 S21: its own notes plus those printed at 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.

From Block S20-S29 Injuries to the thorax applies to 1,602 codes
  • injuries of breast
  • injuries of chest (wall)
  • injuries of interscapular area

Excludes1

Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.

  • traumatic amputation (partial) of thorax (S28.1)

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.

From Block S20-S29 Injuries to the thorax applies to 1,602 codes
  • 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)
From Chapter 19 (S00-T88) Injury, poisoning and certain other consequences of external causes applies to 41,187 codes

Use Additional Code

Add a second code, after this one, to fully describe the condition.

From Chapter 19 (S00-T88) Injury, poisoning and certain other consequences of external causes applies to 41,187 codes
  • 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.

  • 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

Notes

General instructions on how these codes are used.

From Chapter 19 (S00-T88) Injury, poisoning and certain other consequences of external causes applies to 41,187 codes
  • 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 S21
Values for category S21 Encounter: Initial, Subsequent, Sequela
  • Ainitial encounter
  • 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 S21, its category, or a range that includes it.

Code Also 6

These codes say S21 may also be needed to fully describe the condition. The note gives no sequencing direction.

  • S23.1 Subluxation and dislocation of thoracic vertebra
    open wound of thorax (S21.-)
  • S24 Injury of nerves and spinal cord at thorax level
    open wound of thorax (S21.-)
  • S25 Injury of blood vessels of thorax
    any associated open wound (S21.-)
  • S26 Injury of heart
    open wound of thorax (S21.-)
  • S27 Injury of other and unspecified intrathoracic organs
    any associated open wound of thorax (S21.-)
  • S29 Other and unspecified injuries of thorax
    any associated open wound (S21.-)

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 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About S21Overview

What is the ICD-10 code for open wound of thorax?

S21 is the ICD-10-CM category for open wound of thorax, but it is a non-billable header: claims need a more specific code from this category, listed on this page.

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.

Can S21 be reported with S28.1?

Not as a rule. The Excludes1 note on S21 lists "traumatic amputation (partial) of thorax (S28.1)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).