S21
ICD-10Non-billable categoryOpen wound of thorax
Official ICD-10-CM descriptor (FY2026)
Open wound of thorax
S21 is a category heading, not a billable code. CMS does not accept it on a claim; report one of the more specific codes beneath it.
Excludes1
Not coded here. An Excludes1 code should never be reported at the same time as the code above it.
- traumatic amputation (partial) of thorax (S28.1)
Code also
Two codes may be needed; sequencing depends on the reason for the encounter.
- 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
7th character
- The appropriate 7th character is to be added to each code from category S21
Permitted 7th characters
| A | initial encounter |
| D | subsequent encounter |
| S | sequela |
More specific codes under S21
- S21.0Open wound of breastcategory
- S21.1Open wound of front wall of thorax w/o penet thoracic cavitycategory
- S21.2Open wound of back wall of thorax w/o penet thoracic cavitycategory
- S21.3Open wound of front wall of thorax w penet thoracic cavitycategory
- S21.4Open wound of back wall of thorax w penet thoracic cavitycategory
- S21.9Open wound of unspecified part of thoraxcategory
Where this code sits
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ICD-10-CM FY2026. Centers for Medicare & Medicaid Services (CMS) / National Center for Health Statistics (NCHS), “2026 ICD-10-CM Code Descriptions in Tabular Order” (icd10cm_order_2026.txt). Download the original file from cms.gov. Public domain (US Government work). Descriptors, billable flags and instructional notes on this page are reproduced from that file without modification. Krasyn adds no clinical guidance.