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A51 ICD-10-CA category: Early syphilis

A51 isn’t a code on its own. Choose one of the 7 codes beneath it, the one the documentation supports.

Official description

A51

Early syphilis

ICD-10-CA · Canada

Codes in A51

A51 isn’t a code on its own. Open the code that matches what the note documents.

A51.0Primary genital syphilisA51.1Primary anal syphilisA51.2Primary syphilis of other sitesA51.3Secondary syphilis of skin and mucous membranesA51.4Other secondary syphilisA51.5Early syphilis, latentA51.9Early syphilis, unspecified

Notes for A51

As CIHI prints them, with any note A51 takes from the headings above it.

Includes

  • Diseases generally recognized as communicable or transmissibleFrom Chapter 1: Certain infectious and parasitic diseases (A00-B99)

Use additional code

Add a code for this detail when the note documents it.

  • Use additional code (U82-U84) to identify resistance to antimicrobial drugsFrom Chapter 1: Certain infectious and parasitic diseases (A00-B99)

Excludes

Conditions classified elsewhere.

  • Human immunodeficiency virus [HIV] disease (B24)nonspecific and nongonococcal urethritis (N34.1)Reiter disease (M02.3-)From A50-A64 Infections with a predominantly sexual mode of transmission
  • Carrier or suspected carrier of infectious disease (Z22.-)certain localized infections - see body system-related chaptersinfectious and parasitic diseases:• complicating pregnancy, childbirth and the puerperium [except obstetrical tetanus] (O98.-)• specific to the perinatal period [except tetanus neonatorum, whooping cough, congenital syphilis, perinatal gonococcal infection and perinatal human immunodeficiency virus [HIV] disease] (P35-P39)influenza and other acute respiratory infections (J00-J22)From Chapter 1: Certain infectious and parasitic diseases (A00-B99)

Where A51 sits

  1. 1ChapterChapter 1: Certain infectious and parasitic diseases (A00-B99)
  2. 2Block A50-A64Infections with a predominantly sexual mode of transmission
  3. 3Category A51Early syphilis

Source and release

Data release
ICD-10-CA · FY 2026–2027
Effective date
Apr 1, 2026
Publisher
CIHI

This page is built from the ICD-10-CA catalog that Vero Codes reads when it suggests codes: Canadian Institute for Health Information’s FY 2026–2027 release, imported from the publisher’s file and checked against it. The description, notes and structured data come from the same record.

See A51 in the CIHI source

Frequently asked questions

Is A51 a valid ICD-10-CA code?

No. A51 (Early syphilis) is a category heading in CIHI’s ICD-10-CA FY 2026–2027 release. It holds 7 codes; record the one the documentation supports.

Where is A51 in ICD-10-CA?

A51 sits under A50-A64 Infections with a predominantly sexual mode of transmission, within Chapter 1: Certain infectious and parasitic diseases (A00-B99).

What coding notes apply to A51?

ICD-10-CA lists Excludes, Includes, Use additional code notes for A51, including those from the headings it sits under. They are listed on this page with where each one comes from.

Which ICD-10-CA release does this page use?

It uses CIHI’s FY 2026–2027 release, in effect from Apr 1, 2026 to Mar 31, 2027. It is a reference: confirm the code against the current list and the payer’s rules before you submit it.

Codes beside A51

A50Congenital syphilisA52Late syphilisA53Other and unspecified syphilisA54Gonococcal infectionA55Chlamydial lymphogranuloma (venereum)A56Other sexually transmitted chlamydial diseasesA57ChancroidA58Granuloma inguinaleA59TrichomoniasisA60Anogenital herpesviral [herpes simplex] infectionA63Other predominantly sexually transmitted diseases, not elsewhere classifiedA64Unspecified sexually transmitted disease