2026 ICD-10-CM Diagnosis Code A50.6Late congenital syphilis, latent

ICD-10-CM Codes›A00–B99›A50-A64›A50

ICD-10-CM A50.6
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

A50.6 is a billable ICD-10-CM diagnosis code for late congenital syphilis, latent. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 867 through 869. Coders also document this condition as late congenital syphilis. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Perinatal infections and Sexually transmitted infections (excluding HIV and hepatitis).

Code Identity

ICD-10-CM Code
A50.6
Billable Status
Yes — Valid for Submission
Code Describes
Late congenital syphilis, latent
Short Description
Late congenital syphilis, latent
Same as the full description in the CMS dataset.
Parent Code
A50
Congenital syphilis

Code Classification

ChapterA00–B99Certain infectious and parasitic diseases
SectionA50-A64Infections with a predominantly sexual mode of transmission
CategoryA50Congenital syphilis
This CodeA50.6Late congenital syphilis, latent

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Late congenital syphilis
  • Late congenital syphilis, latent
  • Late latent syphilis
  • Latent syphilis
  • Latent syphilis with positive serology

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Inclusion Terms

  • Congenital syphilis without clinical manifestations, with positive serological reaction and negative spinal fluid test, two years or more after birth.

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Syphilis, syphilitic(acquired)
      • congenital
        • late, or 2 years or more after birth NEC
          • latent (without manifestations)
    • Syphilis, syphilitic(acquired)
      • congenital
        • late, or 2 years or more after birth NEC
          • latent (without manifestations)
            • negative spinal fluid test
    • Syphilis, syphilitic(acquired)
      • congenital
        • late, or 2 years or more after birth NEC
          • latent (without manifestations)
            • serology positive

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR PNL009
Perinatal infections
Default principal diagnosis: inpatient Yes · outpatient Yes
CCSR INF010
Sexually transmitted infections (excluding HIV and hepatitis)
Default principal diagnosis: inpatient No · outpatient No

Clinical InformationClinical

  • Late Latent Syphilis

    latent syphilis when infection was acquired more than twelve months previously.

  • Early Latent Syphilis

    latent syphilis when infection was acquired less than twelve months previously.

  • Latent Syphilis

    a stage of syphilis characterized by the serologic evidence of infection by treponema pallidum without evidence of accompanying signs or symptoms related to the disease.

Patient EducationClinical

Syphilis

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.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert A50.6 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
090.6 Late congen syph latent
Exact Match The mapping is direct, with no qualifiers.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About A50.6Overview

Is A50.6 (Congenital syphilis) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report late congenital syphilis, latent on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does A50.6 group to?

When late congenital syphilis, latent is the principal diagnosis on an inpatient stay, it groups to MS-DRG 867, 868, 869, with relative weights from 0.7297 to 2.0932 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of A50.6?

Under the General Equivalence Mappings, late congenital syphilis, latent converts to ICD-9-CM 090.6 (late congen syph latent). The mapping is a direct match.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.