S81.859A (Open bite, unspecified lower leg, initial encounter) compared with S81.859S (Open bite, unspecified lower leg, sequela), from the official CMS tabular data. S81.859A and S81.859S 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. S81.859A and S81.859S 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.
| S81.859AOpen bite, unspecified lower leg, initial encounter | S81.859SOpen bite, unspecified lower leg, 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 | Open bite, unspecified lower leg, initial encounter is a billable ICD-10-CM diagnosis code (S81.859A). | Open bite, unspecified lower leg, sequela is a billable ICD-10-CM diagnosis code (S81.859S). |
| 7th character | The appropriate 7th character is to be added to each code from category S81 | The appropriate 7th character is to be added to each code from category S81 |
Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources