2026 ICD-10-CM Diagnosis Code S21.422DLaceration with foreign body of left back wall of thorax with penetration into thoracic cavity, subsequent encounter

ICD-10-CM Codes›S00–T88›S20-S29›S21

ICD-10-CM S21.422D
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

S21.422D is a billable ICD-10-CM diagnosis code for laceration with foreign body of left back 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 2026 (October 1, 2025 through September 30, 2026) 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

ICD-10-CM Code
S21.422D
Billable Status
Yes — Valid for Submission
Code Describes
Laceration with foreign body of left back wall of thorax with penetration into thoracic cavity, subsequent encounter
Short Description
Lac w fb of l bk wl of thorax w penet thoracic cavity, subs
Parent Code
S21.422
Laceration with foreign body of left back wall of thorax with 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 CodeS21.422DLaceration with foreign body of left back wall of thorax with penetration into thoracic cavity, subsequent encounter

Present on Admission (POA)Billing

S21.422D 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 INJ050
Open wounds of trunk, subsequent encounter
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 S21.422D to ICD-9-CMHistory

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

ICD-9-CM
V58.89 Other specfied aftercare
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 S21.422DOverview

Is S21.422D a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report laceration with foreign body of left back wall of thorax with penetration into thoracic cavity, subsequent encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What does the 7th character D in S21.422D mean?

The final character D marks a subsequent encounter: use it for routine care while the laceration with foreign body of left back wall of thorax with penetration into thoracic cavity is healing, after active treatment has ended.

What MS-DRG does S21.422D group to?

When laceration with foreign body of left back wall of thorax with penetration into thoracic cavity, subsequent encounter is the principal diagnosis on an inpatient stay, it groups to MS-DRG 949, 950, with relative weights from 0.6277 to 1.1897 depending on complications. Higher weights mean higher Medicare reimbursement.

Is S21.422D 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 laceration with foreign body of left back wall of thorax with penetration into thoracic cavity, subsequent encounter on inpatient claims.

What is the ICD-9 equivalent of S21.422D?

Under the General Equivalence Mappings, laceration with foreign body of left back wall of thorax with penetration into thoracic cavity, subsequent encounter converts to ICD-9-CM V58.89 (other specfied aftercare). 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.