Early syphilis (A51)

The ICD-10 code A51 covers all forms of early syphilis, a sexually transmitted infection characterized by distinct stages. This code includes primary syphilis manifestations like chancres at various body sites, as well as secondary symptoms affecting skin, mucous membranes, and other organs.

Specific codes under A51 classify early syphilis conditions in detail. For example, A51.0 is used for primary genital syphilis, also known as syphilitic chancre of penis or vulva. A51.1 refers to primary anal syphilis, commonly called primary extragenital syphilis. A51.2 groups primary syphilis occurring on sites such as the mouth, breast, or fingers. Secondary syphilis, coded as A51.3 and its subcodes, includes manifestations like condyloma latum (A51.31), syphilitic alopecia (A51.32), and other skin or systemic symptoms. Subtypes also identify specific involvement like meningitis (A51.41), pelvic disease (A51.42), and oculopathy (A51.43). Early latent syphilis is coded as A51.5, describing cases with positive serology but no symptoms yet. The code A51.9 is reserved for unspecified early syphilis cases. Using these specific codes helps accurately document the type and location of early syphilis infection, which supports targeted treatment and surveillance.