Early syphilis (A51) ICD-10-CM
The A51 code range covers early syphilis with 18 ICD-10-CM diagnosis codes. 15 of them are billable and valid for claim submission in fiscal year 2026, and the category headers group them but cannot themselves be billed.
Codes in the A51 Range 18 codes · 15 billable
- A51 Early syphilisNon-billable
- A51.0 Primary genital syphilis
- A51.1 Primary anal syphilis
- A51.2 Primary syphilis of other sites
- A51.3 Secondary syphilis of skin and mucous membranesNon-billable
- A51.31 Condyloma latum
- A51.32 Syphilitic alopecia
- A51.39 Other secondary syphilis of skin
- A51.4 Other secondary syphilisNon-billable
- A51.41 Secondary syphilitic meningitis
- A51.42 Secondary syphilitic female pelvic disease
- A51.43 Secondary syphilitic oculopathy
- A51.44 Secondary syphilitic nephritis
- A51.45 Secondary syphilitic hepatitis
- A51.46 Secondary syphilitic osteopathy
- A51.49 Other secondary syphilitic conditions
- A51.5 Early syphilis, latent
- A51.9 Early syphilis, unspecified
Clinical Terms in This Code Range
Definitions from the National Library of Medicine for conditions coded in the A51 range.
Proctocolitis
Inflammation of the RECTUM and the distal portion of the COLON.
About the A51 Code Range
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.
Questions About This Page
How many billable codes are in the A51 range?
Of the 18 codes in this range, 15 are billable and valid for claim submission from October 1, 2025 through September 30, 2026. Category header codes group them but cannot be reported on claims.
What does the A51 range classify?
The range classifies early syphilis. Each code links to its own reference page with billing status, MS-DRG grouping, coding notes, and clinical information.
Related References
Source: CMS FY 2026 ICD-10-CM Tabular List and order file, effective October 1, 2025 through September 30, 2026.
