2026 ICD-10-CM Diagnosis Code S20.343SExternal constriction of bilateral front wall of thorax, sequela

ICD-10-CM Codes›S00–T88›S20-S29›S20

ICD-10-CM S20.343S
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

S20.343S is a billable ICD-10-CM diagnosis code for external constriction of bilateral front wall of thorax, 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
S20.343S
Billable Status
Yes — Valid for Submission
Code Describes
External constriction of bilateral front wall of thorax, sequela
Short Description
External constrict of bi front wall of thorax, sequela
Parent Code
S20.343
External constriction of bilateral front wall of thorax

Code Classification

ChapterS00–T88Injury, poisoning and certain other consequences of external causes
SectionS20-S29Injuries to the thorax
CategoryS20Superficial injury of thorax
This CodeS20.343SExternal constriction of bilateral front wall of thorax, sequela

Present on Admission (POA)Billing

S20.343S 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 Superficial injury of thorax (S20). 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

Code History & ChangesHistory

Replacement S20.343S replaces the following previously assigned code(s):

  • S20.341S - External constriction of right front wall of thorax, sequela
  • S20.342S - External constriction of left front wall of thorax, sequela
FY 2021AddedAdded to the ICD-10-CM code setEffective October 1, 2020.
FY 2022–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About S20.343SOverview

Is S20.343S (External constriction of bilateral front wall of thorax) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report external constriction of bilateral front wall of thorax, sequela on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What does the 7th character S in S20.343S mean?

The final character S makes this a sequela code: it reports a lingering problem that remains after the external constriction of bilateral front wall of thorax itself has resolved, not the original event.

What MS-DRG does S20.343S group to?

When external constriction of bilateral front wall of thorax, 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 S20.343S 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 external constriction of bilateral front wall of thorax, sequela on inpatient claims.

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.