ICD-10-CM 2027 diagnosis code

S21.9Open wound of unspecified part of thorax

Not billable — use a more specific codeRequires 7th character

S21.9 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.

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 S21.9

S21.9 is the ICD-10-CM diagnosis code for open wound of unspecified part of thorax. 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, choose S21.9 (unspecified part of thorax) only when documentation doesn't support a more specific option: 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 back wall of thorax with penetration into thoracic cavity (S21.4).

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

Ainitial encounter
Dsubsequent encounter
Ssequela

Coding notes

Applicable toConditions and synonyms classified to this code

Open wound of thoracic wall NOS

Notes that apply from higher levels

Instructions written at a parent level also apply to S21.9.

› From S21 Open wound of thorax

Excludes1

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

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

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 S21.9

Is S21.9 billable?: No. S21.9 is a header code. Report one of its more specific subcodes instead.