S21 – Open wound of thorax
ICD-10-CM 2027 diagnosis code · Injuries to the thorax
ICD-10-CM code
S21
- Code
S21(claims format:S21)- Description
- Open wound of thorax
- Billable
- No – use a more specific code below
- Valid for
- Dates of service October 1, 2026 – September 30, 2027 (FY2027)
- Chapter
- 19. Injury, poisoning and certain other consequences of external causes (S00-T88)
- Block
- S20-S29 Injuries to the thorax
Billable codes under S21
S21 is a header code and cannot be used on claims. Choose the most specific code:
- S21.0 – Open wound of breastHeader (more codes below)
- S21.1 – Open wound of front wall of thorax without penetration into thoracic cavityHeader (more codes below)
- S21.2 – Open wound of back wall of thorax without penetration into thoracic cavityHeader (more codes below)
- S21.3 – Open wound of front wall of thorax with penetration into thoracic cavityHeader (more codes below)
- S21.4 – Open wound of back wall of thorax with penetration into thoracic cavityHeader (more codes below)
- S21.9 – Open wound of unspecified part of thoraxHeader (more codes below)
7th character values
Codes in this category need a 7th character to describe the encounter or episode of care (use placeholder X for empty positions).
| Character | Meaning |
|---|---|
A | initial encounter |
D | subsequent encounter |
S | sequela |
Notes for S21
Excludes1 (not coded here):
- traumatic amputation (partial) of thorax (S28.1)
Code also:
7th character note:
- The appropriate 7th character is to be added to each code from category S21
Notes inherited from parent codes
Instructional notes at a category or block level apply to every code below it.
Block S20-S29
Includes:
- injuries of breast
- injuries of chest (wall)
- injuries of interscapular area
Excludes2 (not included here):
- 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)
Frequently asked questions
What is ICD-10 code S21?
S21 is the ICD-10-CM code for open wound of thorax, in the block S20-S29 (Injuries to the thorax).
Is S21 a billable code?
No. S21 is a header code with more specific child codes; report one of the billable codes listed above.
Source: CDC/NCHS ICD-10-CM FY2027 code files, tabular list and index. Reference only – code assignment must follow the official ICD-10-CM guidelines and documentation in the medical record.