T59.5X4A (Toxic effect of fluorine gas and hydrogen fluoride, undetermined, initial encounter) compared with T59.5X4S (Toxic effect of fluorine gas and hydrogen fluoride, undetermined, sequela), from the official CMS tabular data. T59.5X4A and T59.5X4S 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. T59.5X4A and T59.5X4S 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.
| T59.5X4AToxic effect of fluorine gas and hydrogen fluoride, undetermined, initial encounter | T59.5X4SToxic effect of fluorine gas and hydrogen fluoride, undetermined, 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 | Toxic effect of fluorine gas and hydrogen fluoride, undetermined, initial encounter is a billable ICD-10-CM diagnosis code (T59.5X4A). | Toxic effect of fluorine gas and hydrogen fluoride, undetermined, sequela is a billable ICD-10-CM diagnosis code (T59.5X4S). |
| 7th character | The appropriate 7th character is to be added to each code from category T59 | The appropriate 7th character is to be added to each code from category T59 |
| Includes | aerosol propellants | aerosol propellants |
| Use additional code | code(s): for all associated manifestations of toxic effect, such as: respiratory conditions due to external agents (J60-J70) personal history of foreign body fully removed (Z87.821) | code(s): for all associated manifestations of toxic effect, such as: respiratory conditions due to external agents (J60-J70) personal history of foreign body fully removed (Z87.821) |
Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources