T78.089A (Anaphylactic reaction due to eggs, unspecified, initial encounter) compared with T78.089D (Anaphylactic reaction due to eggs, unspecified, subsequent encounter), from the official CMS tabular data. T78.089A and T78.089D 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. T78.089A and T78.089D 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.
| T78.089AAnaphylactic reaction due to eggs, unspecified, initial encounter | T78.089DAnaphylactic reaction due to eggs, unspecified, subsequent encounter | |
|---|---|---|
| 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 | Anaphylactic reaction due to eggs, unspecified, initial encounter is a billable ICD-10-CM diagnosis code (T78.089A). | Anaphylactic reaction due to eggs, unspecified, subsequent encounter is a billable ICD-10-CM diagnosis code (T78.089D). |
| 7th character | The appropriate 7th character is to be added to each code from category T78 | The appropriate 7th character is to be added to each code from category T78 |
Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources