2026 ICD-10-CM Diagnosis Code S21.231SPuncture wound without foreign body of right back wall of thorax without penetration into thoracic cavity, sequela

ICD-10-CM Codes›S00–T88›S20-S29›S21

ICD-10-CM S21.231S
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

S21.231S is a billable ICD-10-CM diagnosis code for puncture wound without foreign body of right back wall of thorax without penetration into thoracic cavity, sequela. The 7th character S marks it as a sequela code, which reports a problem that remains after the original condition has resolved. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 604 through 605. The code is exempt from POA reporting. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Injury, sequela.

Code Identity

ICD-10-CM Code
S21.231S
Billable Status
Yes — Valid for Submission
Code Describes
Puncture wound without foreign body of right back wall of thorax without penetration into thoracic cavity, sequela
Short Description
Pnctr w/o fb of r bk wl of thorax w/o penet thor cav, sqla
Parent Code
S21.231
Puncture wound without foreign body of right back wall of thorax without penetration into thoracic cavity

Code Classification

ChapterS00–T88Injury, poisoning and certain other consequences of external causes
SectionS20-S29Injuries to the thorax
CategoryS21Open wound of thorax
This CodeS21.231SPuncture wound without foreign body of right back wall of thorax without penetration into thoracic cavity, sequela

Present on Admission (POA)Billing

S21.231S is exempt from POA reporting on inpatient claims to general acute care hospitals. Review other POA exempt codes.

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 2026, published by CMS and the National Center for Health Statistics.

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR INJ073
Injury, sequela
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Back Injuries

Your back is made of bones, muscles, and other tissues extending from your neck to your pelvis. Back injuries can result from sports injuries, work around the house or in the garden, or a sudden jolt such as a car accident. The lower back is the most common site of back injuries and back pain. Common back injuries include :

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert S21.231S to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
906.0 Lt eff opn wnd head/trnk
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About S21.231SOverview

Is S21.231S a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report puncture wound without foreign body of right back wall of thorax without penetration into thoracic cavity, sequela on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What does the 7th character S in S21.231S mean?

The final character S makes this a sequela code: it reports a lingering problem that remains after the puncture wound without foreign body of right back wall of thorax without penetration into thoracic cavity itself has resolved, not the original event.

What MS-DRG does S21.231S group to?

When puncture wound without foreign body of right back wall of thorax without penetration into thoracic cavity, sequela is the principal diagnosis on an inpatient stay, it groups to MS-DRG 604, 605, with relative weights from 0.9160 to 1.4721 depending on complications. Higher weights mean higher Medicare reimbursement.

Is S21.231S 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 puncture wound without foreign body of right back wall of thorax without penetration into thoracic cavity, sequela on inpatient claims.

What is the ICD-9 equivalent of S21.231S?

Under the General Equivalence Mappings, puncture wound without foreign body of right back wall of thorax without penetration into thoracic cavity, sequela converts to ICD-9-CM 906.0 (lt eff opn wnd head/trnk). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.