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A53.9 — Syphilis, unspecified
A53.9
What this code means
Syphilis is a sexually transmitted bacterial infection that progresses through stages if untreated.
Also called: syphilis.
When this code is used
Used when syphilis is diagnosed without a documented stage or site.
Where it sits in ICD-10-CM
Code A53.9 belongs to Chapter 1: Infectious and parasitic diseases, which covers codes A00–B99 in the FY2027 ICD-10-CM tabular list. The official description above is copied verbatim from the CDC/NCHS FY2027 code file.
Related symptoms
Watch: related videos
Frequently asked questions
What is ICD-10-CM code A53.9?
A53.9 is the ICD-10-CM diagnosis code for “Syphilis, unspecified”. Syphilis is a sexually transmitted bacterial infection that progresses through stages if untreated.
When is code A53.9 used?
Used when syphilis is diagnosed without a documented stage or site. It belongs to Chapter 1 of ICD-10-CM (Infectious and parasitic diseases).
This guide explains ICD-10-CM codes in plain language for patients, students and other readers. It is educational information only — not coding, billing or medical advice. The code recorded for any real encounter is assigned from the full clinical documentation by the treating team and qualified coders, and only they can decide which code fits a specific case.