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A51

Non-billable

Early syphilis

A51 is the ICD-10-CM code for Early syphilis. It is a non-billable category code — use a more specific child code such as A51.0 for billing.

Status
Header (non-billable)
Chapter
A00-B99
Subcodes
7
Edition
FY2026

A00-B99 Certain infectious and parasitic diseases

What this means — in plain language

MedlinePlus · NIH

Syphilis is a sexually transmitted infection (STI) caused by bacteria. It infects the genital area, lips, mouth, or anus of both men and women. You usually get syphilis from sexual contact with someone who has it. It can also pass from mother to baby during pregnancy. The early stage of syphilis usually causes a single, small, painless sore. Sometimes it causes swelling in nearby lymph nodes. If you do not treat it,…

Read more about Syphilis at MedlinePlus ↗

Source: U.S. National Library of Medicine (MedlinePlus). Informational only — not medical advice.

No additional coding notes for this code.

Frequently asked questions

What is ICD-10 code A51?
A51 is the ICD-10-CM code for "Early syphilis". It falls under A00-B99 Certain infectious and parasitic diseases.
Is A51 a billable code?
No — A51 is a non-billable header code. Use a more specific child code (such as A51.0) for billing.
What are the subcodes of A51?
A51 has 7 more specific child codes, including A51.0, A51.1, A51.2.

Source: CMS ICD-10-CM FY2026. For informational purposes only — not medical advice. See our medical disclaimer.

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