ICD-10 Code A51.9 – Early syphilis, unspecified (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code A51.9 – Early syphilis, unspecified
What it is
A51.9 identifies early syphilis when the stage is early, but the specific form is not documented. Use it for confirmed syphilis cases that do not clearly fit primary, secondary, or early latent disease.
Clinical signs
Clinical features vary; refer to documentation. Early syphilis may include chancre, rash, mucous patches, condyloma lata, or other findings consistent with recent infection.
When to use this code
Use this code when the provider documents early syphilis without naming a more specific early stage. It is appropriate when the record confirms syphilis and the timing or presentation supports early infection, but details are incomplete.
If documentation later specifies primary, secondary, or early latent syphilis, code that more specific diagnosis instead. Check documentation for any linked manifestations or additional sites that may require separate coding.
Do not use for
Do not use A51.9 for late syphilis, congenital syphilis, or neurosyphilis. Do not use it when a more specific early syphilis subtype is documented.
Coding tip
When the stage is unclear, query for the exact early syphilis type before defaulting to unspecified.