S81.042A (Puncture wound with foreign body, left knee, initial encounter) compared with S81.042S (Puncture wound with foreign body, left knee, sequela), from the official CMS tabular data. S81.042A and S81.042S code the same injury at a different phase of treatment.
Same underlying diagnosis, different encounter phase.
The 7th character records the phase of care for the encounter being coded, so a single encounter takes one of these characters, not several. Review whether both phases belong on the same episode of care.
Source: ICD-10-CM Official Guidelines, Section I.C.19.a
Same injury, other encounter phase. S81.042A and S81.042S 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.
| S81.042APuncture wound with foreign body, left knee, initial encounter | S81.042SPuncture wound with foreign body, left knee, sequela | |
|---|---|---|
| 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 | Puncture wound with foreign body, left knee, initial encounter is a billable ICD-10-CM diagnosis code (S81.042A). | Puncture wound with foreign body, left knee, sequela is a billable ICD-10-CM diagnosis code (S81.042S). |
| 7th character | The appropriate 7th character is to be added to each code from category S81 | The appropriate 7th character is to be added to each code from category S81 |
Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources