T34.829A (Frostbite with tissue necrosis of unspecified foot, initial encounter) compared with T34.829S (Frostbite with tissue necrosis of unspecified foot, sequela), from the official CMS tabular data. T34.829A and T34.829S 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. T34.829A and T34.829S 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.
| T34.829AFrostbite with tissue necrosis of unspecified foot, initial encounter | T34.829SFrostbite with tissue necrosis of unspecified foot, 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 | Frostbite with tissue necrosis of unspecified foot, initial encounter is a billable ICD-10-CM diagnosis code (T34.829A). | Frostbite with tissue necrosis of unspecified foot, sequela is a billable ICD-10-CM diagnosis code (T34.829S). |
| 7th character | The appropriate 7th character is to be added to each code from category T34 | The appropriate 7th character is to be added to each code from category T34 |
Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources