T33.90XA (Superficial frostbite of unspecified sites, initial encounter) compared with T33.90XS (Superficial frostbite of unspecified sites, sequela), from the official CMS tabular data. T33.90XA and T33.90XS 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. T33.90XA and T33.90XS 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.
| T33.90XASuperficial frostbite of unspecified sites, initial encounter | T33.90XSSuperficial frostbite of unspecified sites, 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 | Superficial frostbite of unspecified sites, initial encounter is a billable ICD-10-CM diagnosis code (T33.90A). | Superficial frostbite of unspecified sites, sequela is a billable ICD-10-CM diagnosis code (T33.90S). |
| 7th character | The appropriate 7th character is to be added to each code from category T33 | The appropriate 7th character is to be added to each code from category T33 |
| Includes | frostbite with partial thickness skin loss Superficial frostbite NOS | frostbite with partial thickness skin loss Superficial frostbite NOS |
Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources