S85.161A (Unspecified injury of posterior tibial artery, right leg, initial encounter) compared with S85.161S (Unspecified injury of posterior tibial artery, right leg, sequela), from the official CMS tabular data. S85.161A and S85.161S 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. S85.161A and S85.161S 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.
| S85.161AUnspecified injury of posterior tibial artery, right leg, initial encounter | S85.161SUnspecified injury of posterior tibial artery, right 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 | Unspecified injury of posterior tibial artery, right leg, initial encounter is a billable ICD-10-CM diagnosis code (S85.161A). | Unspecified injury of posterior tibial artery, right leg, sequela is a billable ICD-10-CM diagnosis code (S85.161S). |
| 7th character | The appropriate 7th character is to be added to each code from category S85 | The appropriate 7th character is to be added to each code from category S85 |
Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources