T28.90XA (Corrosions of unspecified internal organs, initial encounter) compared with T28.90XS (Corrosions of unspecified internal organs, sequela), from the official CMS tabular data. T28.90XA and T28.90XS code the same injury at a different phase of treatment. MedCoder-derived
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. T28.90XA and T28.90XS 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.
| T28.90XACorrosions of unspecified internal organs, initial encounter | T28.90XSCorrosions of unspecified internal organs, sequela | |
|---|---|---|
| Billing status | Billable | Billable |
| Classification | S00-T88 — Injury, poisoning and certain other consequences of external causes | S00-T88 — Injury, poisoning and certain other consequences of external causes |
| Definition | Corrosions of unspecified internal organs, initial encounter is a billable ICD-10-CM diagnosis code (T28.90A). | Corrosions of unspecified internal organs, sequela is a billable ICD-10-CM diagnosis code (T28.90S). |
| 7th character | The appropriate 7th character is to be added to each code from category T28 | The appropriate 7th character is to be added to each code from category T28 |
| Use additional code | external cause code to identify the source and intent of the burn (X00-X19, X75-X77, X96-X98) external cause code to identify place (Y92) | external cause code to identify the source and intent of the burn (X00-X19, X75-X77, X96-X98) external cause code to identify place (Y92) |
| Code first | (T51-T65) to identify chemical and intent | (T51-T65) to identify chemical and intent |
Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources