ICD-10-CM 2027 diagnosis code
S21.4Open wound of back wall of thorax with penetration into thoracic cavity
S21.4 is a header code, so it can't be reported by itself. Choose one of the 6 more specific codes beneath it and add the required 7th character.Short description: Open wound of back wall of thorax w penet thoracic cavity
Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data
About S21.4
S21.4 is the ICD-10-CM diagnosis code for open wound of back wall of thorax with penetration into thoracic cavity. It belongs to category S21 (open wound of thorax), block S20-S29 (injuries to the thorax) and chapter 19 (injury, poisoning and certain other consequences of external causes). It is a header code, so it can't be reported by itself; one of its 6 subcodes must be used instead.
Within S21 (open wound of thorax), S21.4 is specifically for open wound of back wall of thorax with penetration into thoracic cavity. Related codes cover breast (S21.0), front wall of thorax without penetration into thoracic cavity (S21.1), back wall of thorax without penetration into thoracic cavity (S21.2), front wall of thorax with penetration into thoracic cavity (S21.3) and unspecified part of thorax (S21.9).
Codes in this range require a 7th character: A for initial encounter, D for subsequent encounter and S for sequela. Use placeholder "X" characters to fill any empty positions before the 7th character.
It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.
7th character
The appropriate 7th character is to be added to each code from category S21
- S21.40Unspecified open wound of back wall of thorax with penetration into thoracic cavity
- S21.41Laceration without foreign body of back wall of thorax with penetration into thoracic cavity
- S21.411Laceration without foreign body of right back wall of thorax with penetration into thoracic cavity
- S21.412Laceration without foreign body of left back wall of thorax with penetration into thoracic cavity
- S21.419Laceration without foreign body of unspecified back wall of thorax with penetration into thoracic cavity
- S21.42Laceration with foreign body of back wall of thorax with penetration into thoracic cavity
- S21.421Laceration with foreign body of right back wall of thorax with penetration into thoracic cavity
- S21.422Laceration with foreign body of left back wall of thorax with penetration into thoracic cavity
- S21.429Laceration with foreign body of unspecified back wall of thorax with penetration into thoracic cavity
- S21.43Puncture wound without foreign body of back wall of thorax with penetration into thoracic cavity
- S21.431Puncture wound without foreign body of right back wall of thorax with penetration into thoracic cavity
- S21.432Puncture wound without foreign body of left back wall of thorax with penetration into thoracic cavity
- S21.439Puncture wound without foreign body of unspecified back wall of thorax with penetration into thoracic cavity
- S21.44Puncture wound with foreign body of back wall of thorax with penetration into thoracic cavity
- S21.441Puncture wound with foreign body of right back wall of thorax with penetration into thoracic cavity
- S21.442Puncture wound with foreign body of left back wall of thorax with penetration into thoracic cavity
- S21.449Puncture wound with foreign body of unspecified back wall of thorax with penetration into thoracic cavity
- S21.45Open bite of back wall of thorax with penetration into thoracic cavity
- Ainitial encounter
- Dsubsequent encounter
- Ssequela
Notes that apply from higher levels
Instructions written at a parent level also apply to S21.4.
› From S21 Open wound of thorax
- traumatic amputation (partial) of thorax (S28.1)
Broader instructions also apply from S20-S29 Injuries to the thorax and Chapter 19: Injury, poisoning and certain other consequences of external causes.
Code history
- 2016
- 2017
- 2018
- 2019
- 2020
- 2021
- 2022
- 2023
- 2024
- 2025
- 2026
- 2027
- FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
- No changes since FY2016.
Common questions about S21.4
Is S21.4 billable?
- No. S21.4 is a header code. Report one of its more specific subcodes instead.