A51.0 vs N77.0
A51.0 (Primary genital syphilis) compared with N77.0 (Ulceration of vulva in diseases classified elsewhere), from the official CMS tabular data. Do not report these codes together: the official tabular list marks them Excludes1.
Can these codes be reported together?
No — do not report together. N77.0 carries an Excludes1 note covering A51.0: “ulceration of vulva in syphilis (A51.0)”
Sole exception: when the two conditions are documented as unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).
Side by side
| A51.0Primary genital syphilis | N77.0Ulceration of vulva in diseases classified elsewhere | |
|---|---|---|
| Billing status | Billable | Billable |
| Classification | A00-B99 — Certain Infectious and Parasitic Diseases (A00-B99) | N00-N99 — Diseases of the Genitourinary System (N00-N99) |
| Definition | Primary genital syphilis is a billable ICD-10-CM diagnosis code (A51.0). | Ulceration of vulva in diseases classified elsewhere is a billable ICD-10-CM diagnosis code (N77.0). |
| Includes | Syphilitic chancre NOS | — |
| Code first | — | underlying disease, such as: Behçet's disease (M35.2) |
Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources