S13.180A (Subluxation of C7/T1 cervical vertebrae, initial encounter) compared with S13.180D (Subluxation of C7/T1 cervical vertebrae, subsequent encounter), from the official CMS tabular data. S13.180A and S13.180D 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. S13.180A and S13.180D 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.
| S13.180ASubluxation of C7/T1 cervical vertebrae, initial encounter | S13.180DSubluxation of C7/T1 cervical vertebrae, 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 | Subluxation of C7/T1 cervical vertebrae, initial encounter is a billable ICD-10-CM diagnosis code (S13.180A). | Subluxation of C7/T1 cervical vertebrae, subsequent encounter is a billable ICD-10-CM diagnosis code (S13.180D). |
| 7th character | The appropriate 7th character is to be added to each code from category S13 | The appropriate 7th character is to be added to each code from category S13 |
| Includes | avulsion of joint or ligament at neck level laceration of cartilage, joint or ligament at neck level sprain of cartilage, joint or ligament at neck level traumatic hemarthrosis of joint or ligament at neck level | avulsion of joint or ligament at neck level laceration of cartilage, joint or ligament at neck level sprain of cartilage, joint or ligament at neck level traumatic hemarthrosis of joint or ligament at neck level |
Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources