2027 ICD-10-CM Diagnosis Code S21.301DUnspecified open wound of right front wall of thorax with penetration into thoracic cavity, subsequent encounter
S21.301D is a billable ICD-10-CM diagnosis code for unspecified open wound of right front wall of thorax with penetration into thoracic cavity, subsequent encounter. The 7th character D marks it as a subsequent encounter code, used during routine care in the healing or recovery phase. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 949 through 950. The code is exempt from POA reporting. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Open wounds of trunk, subsequent encounter.
Code Identity
Code Classification
Present on Admission (POA)Billing
S21.301D is exempt from POA reporting on inpatient claims to general acute care hospitals. Review the other POA exempt codes in Injuries to the thorax (S20-S29).
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 S21.301D: its own notes plus those printed at S21, 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.
- 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.
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.
- 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)
Use Additional Code
Add a second code, after this one, to fully describe the condition.
- 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.
Notes
General instructions on how these codes are used.
- 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
- Ainitial encounter
- Dsubsequent encounter this code
- 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 S21.301D, its category, or a range that includes it.
Code Also 6
These codes say S21.301D may also be needed to fully describe the condition. The note gives no sequencing direction.
- S23.1 Subluxation and dislocation of thoracic vertebraopen wound of thorax (S21.-) names S21.-, which includes this code
- S24 Injury of nerves and spinal cord at thorax levelopen wound of thorax (S21.-) names S21.-, which includes this code
- S25 Injury of blood vessels of thoraxany associated open wound (S21.-) names S21.-, which includes this code
- S26 Injury of heartopen wound of thorax (S21.-) names S21.-, which includes this code
- S27 Injury of other and unspecified intrathoracic organsany associated open wound of thorax (S21.-) names S21.-, which includes this code
- S29 Other and unspecified injuries of thoraxany associated open wound (S21.-) names S21.-, which includes this code
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
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.
Convert S21.301D to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About S21.301DOverview
Is S21.301D a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report unspecified open wound of right front wall of thorax with penetration into thoracic cavity, subsequent encounter on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What does the 7th character D in S21.301D mean?
The final character D marks a subsequent encounter: use it for routine care while the unspecified open wound of right front wall of thorax with penetration into thoracic cavity is healing, after active treatment has ended.
What MS-DRG does S21.301D group to?
When unspecified open wound of right front wall of thorax with penetration into thoracic cavity, subsequent encounter is the principal diagnosis on an inpatient stay, it groups to MS-DRG 950, 949, with relative weights from 0.7661 to 1.1231 depending on complications. Higher weights mean higher Medicare reimbursement.
Is S21.301D exempt from POA reporting?
Yes. CMS lists this code among those exempt from present on admission reporting, so hospitals do not assign a POA indicator for unspecified open wound of right front wall of thorax with penetration into thoracic cavity, subsequent encounter on inpatient claims. The code appears in the Injuries to the thorax (S20-S29) range of the CMS exempt list.
Can S21.301D be reported with S28.1?
Not as a rule. The Excludes1 note at S21, which applies to S21.301D, 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).
