S21.401A vs S21.401D
S21.401A (Unspecified open wound of right back wall of thorax with penetration into thoracic cavity, initial encounter) compared with S21.401D (Unspecified open wound of right back wall of thorax with penetration into thoracic cavity, subsequent encounter), from the official CMS tabular data. S21.401A and S21.401D code the same injury at a different phase of treatment.
Can these codes be reported together?
Same injury, other encounter phase. S21.401A and S21.401D code the same injury at a different phase of treatment, set by the 7th character.
The 7th character records the type of care given at the encounter being coded (ICD-10-CM Official Guidelines, Section I.C.19.a), so one encounter takes one of these, not both.
Side by side
| S21.401AUnspecified open wound of right back wall of thorax with penetration into thoracic cavity, initial encounter | S21.401DUnspecified open wound of right back wall of thorax with penetration into thoracic cavity, subsequent encounter | |
|---|---|---|
| Billing status | Billable | Billable |
| Classification | S00-T88 — Injury, Poisoning and Certain Other Consequences of External Causes (S00-T88) | S00-T88 — Injury, Poisoning and Certain Other Consequences of External Causes (S00-T88) |
| Definition | Unspecified 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 right back wall of thorax with penetration into thoracic cavity, subsequent encounter is a billable ICD-10-CM diagnosis code (S21.401D). |
| 7th character | The appropriate 7th character is to be added to each code from category S21 | The 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 |
Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources