Early syphilis ICD-10-CM Coding & Reimbursement Guide

International Classification of Diseases, 10th Revision, Clinical Modification (ICD-10-CM) codes under the group ICD-10-CM A51 encompass early syphilis infections including primary, secondary, and early latent stages, characterized by localized and systemic manifestations following sexual transmission. Accurate ICD-10-CM coding for this group is important for appropriate claim adjudication and correct assignment of reimbursement based on disease staging and documented services.

Early syphilis Overview

The diagnoses in ICD-10-CM A51 represent early stages of syphilis infection, including primary, secondary, and early latent syphilis, caused by the bacterium Treponema pallidum and transmitted predominantly through sexual contact. These conditions affect the integumentary and systemic domains with manifestations such as chancres, mucocutaneous lesions, and regional lymphadenopathy. Accurate coding ensures proper classification of disease stage and treatment timing, which can affect clinical tracking and reimbursement determinations.

A sexually active adult presents to the urgent care clinic with a painless genital ulcer (chancre) of recent onset and painless regional lymphadenopathy after a high-risk sexual exposure. Serologic testing is pending but dark-field microscopy or direct detection confirms Treponema pallidum; the encounter documents early primary disease. A diagnosis from this group is assigned for primary syphilis, typically coded as A510.
A pregnant person is evaluated at a prenatal visit for a painless genital lesion and positive non-treponemal and treponemal serologies consistent with secondary mucocutaneous manifestations after recent infection; management considerations focus on staging and treatment to prevent congenital transmission. This presentation represents secondary early syphilis with mucocutaneous signs and systemic symptoms, and one of the codes for secondary disease is used, such as A5139 or A511 depending on documented manifestations.
A patient with HIV infection presents to the clinic with multiple condylomata lata on the perineum and generalized rash following a recent sexual exposure; clinicians document early syphilis with cutaneous involvement in a person with immunocompromise, which can alter presentation and urgency of treatment. Because this is early syphilis with mucocutaneous lesions in a person with comorbidity, codes like A5131, A5132, or A5139 are considered depending on lesion location and specificity.

ICD-10-CM codes are structured hierarchically — each code begins with a letter representing the chapter, followed by two digits identifying the category, then a decimal point and additional characters that specify the exact condition, site, and any relevant detail such as laterality or episode of care. Every code in this table shares the same category characters, meaning they all describe variations of the same underlying diagnosis. The remaining characters distinguish specific manifestations, anatomical sites, or clinical circumstances within that category.

Description
Primary genital syphilis
Primary anal syphilis
Primary syphilis of other sites
Condyloma latum
Syphilitic alopecia
Other secondary syphilis of skin
Secondary syphilitic meningitis
Secondary syphilitic female pelvic disease
Secondary syphilitic oculopathy
Secondary syphilitic nephritis
Secondary syphilitic hepatitis
Secondary syphilitic osteopathy
Other secondary syphilitic conditions
Early syphilis, latent
Early syphilis, unspecified

DRG	Description
DRG 023	Craniotomy with Major Device Implant or Acute Complex CNS Principal Diagnosis with MCC or Antineoplastic Implant or Epilepsy with Neurostimulator
DRG 024	Craniotomy with Major Device Implant or Acute Complex CNS Principal Diagnosis without MCC
DRG 097	Non-Bacterial Infection of Nervous System Except Viral Meningitis with MCC
DRG 098	Non-Bacterial Infection of Nervous System Except Viral Meningitis with CC
DRG 099	Non-Bacterial Infection of Nervous System Except Viral Meningitis without CC/MCC
DRG 124	Other Disorders of the Eye with MCC or Thrombolytic Agent
DRG 125	Other Disorders of the Eye without MCC
DRG 393	Other Digestive System Diagnoses with MCC
DRG 394	Other Digestive System Diagnoses with CC
DRG 395	Other Digestive System Diagnoses without CC/MCC
DRG 441	Disorders of Liver Except Malignancy, Cirrhosis or Alcoholic Hepatitis with MCC
DRG 442	Disorders of Liver Except Malignancy, Cirrhosis or Alcoholic Hepatitis with CC
DRG 443	Disorders of Liver Except Malignancy, Cirrhosis or Alcoholic Hepatitis without CC/MCC
DRG 539	Osteomyelitis with MCC
DRG 540	Osteomyelitis with CC
DRG 541	Osteomyelitis without CC/MCC
DRG 606	Minor Skin Disorders with MCC
DRG 607	Minor Skin Disorders without MCC
DRG 727	Inflammation of the Male Reproductive System with MCC
DRG 728	Inflammation of the Male Reproductive System without MCC
DRG 742	Uterine and Adnexa Procedures for Non-Malignancy with CC/MCC
DRG 743	Uterine and Adnexa Procedures for Non-Malignancy without CC/MCC
DRG 757	Infections, Female Reproductive System with MCC
DRG 758	Infections, Female Reproductive System with CC
DRG 759	Infections, Female Reproductive System without CC/MCC
DRG 867	Other Infectious and Parasitic Diseases Diagnoses with MCC
DRG 868	Other Infectious and Parasitic Diseases Diagnoses with CC
DRG 869	Other Infectious and Parasitic Diseases Diagnoses without CC/MCC

When a diagnosis from this group is reported on an inpatient claim, the CMS MS-DRG grouper evaluates the principal diagnosis, procedure codes, and the presence of complicating conditions (CC) or major complicating conditions (MCC) to assign a Diagnosis-Related Group. The DRGs listed above represent the possible MS-DRG assignments for diagnoses in this group. Each DRG carries a relative weight used to calculate the Medicare inpatient prospective payment.

Description
Primary genital syphilis
Primary anal syphilis
Primary syphilis of other sites
Condyloma latum
Syphilitic alopecia
Other secondary syphilis of skin
Secondary syphilitic meningitis
Secondary syphilitic female pelvic disease
Secondary syphilitic oculopathy
Secondary syphilitic nephritis
Secondary syphilitic hepatitis
Secondary syphilitic osteopathy
Other secondary syphilitic conditions
Early syphilis, latent
Early syphilis, unspecified

DRG	Description
DRG 023	Craniotomy with Major Device Implant or Acute Complex CNS Principal Diagnosis with MCC or Antineoplastic Implant or Epilepsy with Neurostimulator
DRG 024	Craniotomy with Major Device Implant or Acute Complex CNS Principal Diagnosis without MCC
DRG 097	Non-Bacterial Infection of Nervous System Except Viral Meningitis with MCC
DRG 098	Non-Bacterial Infection of Nervous System Except Viral Meningitis with CC
DRG 099	Non-Bacterial Infection of Nervous System Except Viral Meningitis without CC/MCC
DRG 124	Other Disorders of the Eye with MCC or Thrombolytic Agent
DRG 125	Other Disorders of the Eye without MCC
DRG 393	Other Digestive System Diagnoses with MCC
DRG 394	Other Digestive System Diagnoses with CC
DRG 395	Other Digestive System Diagnoses without CC/MCC
DRG 441	Disorders of Liver Except Malignancy, Cirrhosis or Alcoholic Hepatitis with MCC
DRG 442	Disorders of Liver Except Malignancy, Cirrhosis or Alcoholic Hepatitis with CC
DRG 443	Disorders of Liver Except Malignancy, Cirrhosis or Alcoholic Hepatitis without CC/MCC
DRG 539	Osteomyelitis with MCC
DRG 540	Osteomyelitis with CC
DRG 541	Osteomyelitis without CC/MCC
DRG 606	Minor Skin Disorders with MCC
DRG 607	Minor Skin Disorders without MCC
DRG 727	Inflammation of the Male Reproductive System with MCC
DRG 728	Inflammation of the Male Reproductive System without MCC
DRG 742	Uterine and Adnexa Procedures for Non-Malignancy with CC/MCC
DRG 743	Uterine and Adnexa Procedures for Non-Malignancy without CC/MCC
DRG 757	Infections, Female Reproductive System with MCC
DRG 758	Infections, Female Reproductive System with CC
DRG 759	Infections, Female Reproductive System without CC/MCC
DRG 867	Other Infectious and Parasitic Diseases Diagnoses with MCC
DRG 868	Other Infectious and Parasitic Diseases Diagnoses with CC
DRG 869	Other Infectious and Parasitic Diseases Diagnoses without CC/MCC

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Summary & Overview

Early syphilis: ICD-10-CM Diagnosis Code Group Overview

Early syphilis Overview

Typical Clinical Scenarios

ICD-10-CM Codes

DRG Codes

ICD-10-CM Codes

DRG Codes