T33.42XA (Superficial frostbite of left arm, initial encounter) compared with T33.42XS (Superficial frostbite of left arm, sequela), from the official CMS tabular data. T33.42XA and T33.42XS 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. T33.42XA and T33.42XS 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.
| T33.42XASuperficial frostbite of left arm, initial encounter | T33.42XSSuperficial frostbite of left arm, 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 | Superficial frostbite of left arm, initial encounter is a billable ICD-10-CM diagnosis code (T33.42A). | Superficial frostbite of left arm, sequela is a billable ICD-10-CM diagnosis code (T33.42S). |
| 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 | frostbite with partial thickness skin loss |
Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources