Unspecified sexually transmitted disease
In Infections with a predominantly sexual mode of transmission (A50-A64), chapter 1: Certain Infectious and Parasitic Diseases
- A64 is an unspecified code: use it only when the record doesn't document anything more specific. If the record has more detail, check the other codes under A50-A64 below.
- As a secondary diagnosis it is not a CC or MCC, so it doesn't raise the MS-DRG payment.
- Doesn't count toward a Medicare Advantage risk score (no HCC in V28).
- AHRQ's Chronic Condition Indicator classes it as not chronic (an acute or short-term condition).
Also indexed as: Disease, sexually transmitted; Disease, venereal; Venereal, disease
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Instructional notes
Also applies, from Infections with a predominantly sexual mode of transmission (A50-A64)
These notes sit on A50-A64 and apply to every code under it, including A64.
Official coding guidelines
From the ICD-10-CM Official Guidelines for Coding and Reporting, FY 2027 (CMS and NCHS). Links open the PDF at the right page.
Rules for coding infections and parasitic diseases, including HIV, organism and drug resistance codes, sepsis and septic shock, MRSA, Zika, and COVID-19.
- Human Immunodeficiency Virus (HIV) Infections (page 19)
- Infectious agents as the cause of diseases classified to other chapters (page 22)
- Infections resistant to antibiotics (page 22)
- Sepsis, Severe Sepsis, and Septic Shock (page 23)
- Methicillin Resistant Staphylococcus aureus (MRSA) Conditions (page 27)
- Zika virus infections (page 28)
- Coronavirus infections (page 28)
Other codes under A50-A64
Infections with a predominantly sexual mode of transmission (A50-A64)
- A50Congenital syphilis
- A51Early syphilis
- A52Late syphilis
- A53Other and unspecified syphilis
- A54Gonococcal infection
- A55Chlamydial lymphogranuloma (venereum)
- A56Other sexually transmitted chlamydial diseases
- A57Chancroid
- A58Granuloma inguinale
- A59Trichomoniasis
- A60Anogenital herpesviral [herpes simplex] infections
- A63Other predominantly sexually transmitted diseases, not elsewhere classified
- A64Unspecified sexually transmitted disease(this code)
A64 MS-DRGs
As the principal diagnosis, A64 groups to these 7 MS-DRGs (v44.0). Which one applies depends on procedures performed, secondary diagnoses (CC/MCC), and the patient's age and discharge status.
- 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
Related conditions
Grouped by AHRQ's Clinical Classifications Software Refined (CCSR), which sorts every diagnosis code into clinically meaningful categories.
A64 is in Sexually transmitted infections (excluding HIV and hepatitis) (INF010, its default category), with 160 codes. Others in it:
- A50.01 Early congenital syphilitic oculopathy
- A50.02 Early congenital syphilitic osteochondropathy
- A50.03 Early congenital syphilitic pharyngitis
- A50.04 Early congenital syphilitic pneumonia
- A50.05 Early congenital syphilitic rhinitis
- A50.06 Early cutaneous congenital syphilis
- A50.07 Early mucocutaneous congenital syphilis
- A50.08 Early visceral congenital syphilis
Other codes that refer to A64
Notes on these codes point to A64.
About the condition
Plain-language background from MedlinePlus (National Library of Medicine), not coding guidance.
Sexually Transmitted Infections
Sexually transmitted infections (STIs) are infections that are passed from one person to another through sexual contact. If not treated, an STI can develop into a sexually transmitted disease (STD).
Read more about sexually transmitted infections on MedlinePlusCode history
Valid since FY2016, when ICD-10-CM took effect on October 1, 2015. No changes since.
ICD-9-CM equivalent
Legacy crosswalk from the CMS General Equivalence Mappings (last updated 2018).
- 099.9 Venereal disease, unspecified