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S21.401A vs S21.409A

S21.401A (Unspecified open wound of right back wall of thorax with penetration into thoracic cavity, initial encounter) compared with S21.409A (Unspecified open wound of unspecified back wall of thorax with penetration into thoracic cavity, initial encounter), from the official CMS tabular data. S21.401A and S21.409A code the same condition on opposite sides. MedCoder-derived

Relationship

Review

Laterality relationship

S21.401A
Right
Unspecified open wound of right back wall of thorax with penetration into thoracic cavity, initial encounter
↔
S21.409A
Unspecified
Unspecified open wound of unspecified back wall of thorax with penetration into thoracic cavity, initial encounter

Same condition; these differ only in which side is documented.

These codes share a category and title and differ only in the side affected. The documentation decides which applies, and a bilateral code is reported only where the code set provides one.

Source: ICD-10-CM tabular list (laterality variant derived from the code title)

Can these codes be reported together?

Same condition, opposite side. S21.401A and S21.409A name the same condition on opposite sides of the body.

Same category and title, differing only in which side is affected — the documentation decides which one applies, and a bilateral code is reported only where the code set provides one.

Side by side

S21.401AUnspecified open wound of right back wall of thorax with penetration into thoracic cavity, initial encounterS21.409AUnspecified open wound of unspecified back wall of thorax with penetration into thoracic cavity, initial encounter
Billing statusBillableBillable
ClassificationS00-T88 — Injury, poisoning and certain other consequences of external causesS00-T88 — Injury, poisoning and certain other consequences of external causes
DefinitionUnspecified open wound of right back wall of thorax with penetration into thoracic cavity, initial encounter is a billable ICD-10-CM diagnosis code (S21.401A).Unspecified open wound of unspecified back wall of thorax with penetration into thoracic cavity, initial encounter is a billable ICD-10-CM diagnosis code (S21.409A).
7th characterThe appropriate 7th character is to be added to each code from category S21The appropriate 7th character is to be added to each code from category S21
Includes
injuries of breast
injuries of chest (wall)
injuries of interscapular area
injuries of breast
injuries of chest (wall)
injuries of interscapular area
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Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources