2027 ICD-10-CM Diagnosis Code A51.5Early syphilis, latent
ICD-10-CM Codes›A00–B99›A50-A64›A51
- Billable — Valid for Submission
- Not Chronic
A51.5 is a billable ICD-10-CM diagnosis code for early syphilis, latent. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 867 through 869. Coders also document this condition as acquired syphilis. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Sexually transmitted infections (excluding HIV and hepatitis).
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Acquired syphilis
- Acquired syphilis - early latent
- Early latent syphilis, positive serology, negative cerebrospinal fluid, less than 2 years after infection
- Early latent syphilis, positive serology, negative cerebrospinal fluid, with relapse after treatment
- Latent early syphilis
- Latent syphilis
- Latent syphilis with positive serology
- Serological relapse after treatment of latent early syphilis
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to A51.5: its own notes plus those printed at block A50-A64 and Chapter 1. A note printed at a category, block or chapter applies to every code under it.
Includes
Further defines, or gives examples of, the content of the category.
- diseases generally recognized as communicable or transmissible
Applicable To
Conditions this code is used for: synonyms of the title or, for "other specified" codes, the conditions assigned to it. The list is not exhaustive.
- Syphilis (acquired) without clinical manifestations, with positive serological reaction and negative spinal fluid test, less than two years after infection.
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.
- human immunodeficiency virus [HIV] disease (B20)
- carrier or suspected carrier of infectious disease (Z22.-)
- certain localized infections - see body system-related chapters
- infectious and parasitic diseases complicating pregnancy, childbirth and the puerperium (O98.-)
- infectious and parasitic diseases specific to the perinatal period (P35-P39)
- influenza and other acute respiratory infections (J00-J22)
Use Additional Code
Add a second code, after this one, to fully describe the condition.
- code to identify resistance to antimicrobial drugs (Z16.-)
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name A51.5, its category, or a range that includes it.
Applicable To 1
These notes mention A51.5.
- O98.1 Syphilis complicating pregnancy, childbirth and the puerperium
Excludes2 1
These codes carry an Excludes2 note naming A51.5: its condition is not part of those codes, and both may be reported when the patient has both.
- Block A65-A69 Other spirochetal diseases
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
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 A51.5 to ICD-9-CMHistory
Code HistoryHistory
Questions About A51.5Overview
What is the ICD-10 code for early syphilis, latent?
The ICD-10-CM code for early syphilis, latent is A51.5 (sometimes written as A515). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is A51.5 (Early syphilis) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report early syphilis, latent on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does A51.5 group to?
When early syphilis, latent is the principal diagnosis on an inpatient stay, it groups to MS-DRG 867, 869, 868, with relative weights from 0.6784 to 2.1855 depending on complications. Higher weights mean higher Medicare reimbursement.
Can A51.5 be reported with N34.1?
Not as a rule. The Excludes1 note at block A50-A64, which applies to A51.5, lists "nonspecific and nongonococcal urethritis (N34.1)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).
What is the ICD-9 equivalent of A51.5?
Under the General Equivalence Mappings, early syphilis, latent converts to ICD-9-CM 092.0 (early syph latent relaps) and 092.9 (early syphil latent NOS). The mapping is approximate, so confirm the match fits the documentation.
