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Chlamydia Antibody, Genital Site (Qualitative Immunoassay)

Published: August 9, 2026Updated: August 16, 2026

This test detects antibodies to *Chlamydia trachomatis*, a bacterium that can cause infections like chlamydia in the genital area. Antibodies indicate past or current exposure.

Quick summary

["This test helps diagnose chlamydia infection by checking for immune system response to the bacteria."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
31765-1
Short code
CHLAG
Synonyms
Chlamydia Ag Genital Ql
Category
chemistry
Sample
serum
Container
Genital swab collected in Chlamydia transport medium, viral transport medium, or sterile container appropriate for the testing methodology. NAAT specimens require specific collection kits provided by the testing laboratory.
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
≥ 13 years
Method
Direct immunofluorescence assay (DFA), enzyme immunoassay (EIA), or nucleic acid amplification test (NAAT) for Chlamydia species antigen detection
CPT
87320
SNOMED
310861008
Specimen volume
Not applicable; qualitative test requiring adequate cellular material from swab specimen. Minimum volume requirements depend on assay manufacturer specifications.
Stability
Specimens should be transported to the laboratory as soon as possible after collection. Refrigerated (2-8°C) stability typically up to 48-72 hours depending on transport medium. For NAAT, refer to manufacturer guidelines; generally stable at 2-30°C for specified timeframes. Frozen specimens are generally not recommended unless specified by the assay.
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–72 hours
Order
routine

What This Test Measures

The test looks for specific antibodies produced by your immune system in response to *Chlamydia trachomatis*. These antibodies are a sign that your body has encountered the bacteria, either through past infection or ongoing exposure.

Why It’s Done

Your healthcare provider may order this test if you have symptoms of chlamydia (e.g., unusual discharge, pain during urination) or if you’re at higher risk (e.g., sexually active without protection, multiple partners). It can also be part of routine screening for sexually transmitted infections.

How It Works

A small blood sample is taken from a vein in your arm. The sample is then tested using an immunoassay method to detect antibodies against *Chlamydia trachomatis*. The result is qualitative (positive or negative) rather than a measured quantity.

What the Results Mean

A **positive** result means you likely had or are currently infected with chlamydia. A **negative** result suggests no current infection, but it does not rule out past exposure. Follow-up testing or treatment may be recommended based on clinical judgment.

Reference range

Negative (no Chlamydia antigen detected). Positive results indicate the presence of Chlamydia species antigen in the genital specimen.N/A

Specimen: serum

Patient should abstain from sexual intercourse for at least 24 hours prior to specimen collection. Avoid douching, vaginal creams, or medications for 24-48 hours before collection. For female patients, specimen should not be collected during menstruation if possible. For male patients, patient should not have urinated within 1-2 hours prior to urethral specimen collection.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Chlamydia Antibody (Genital)

Frequently asked questions

What symptoms might this test be done for?
This test is often done to diagnose chlamydia infection, which can cause pelvic inflammatory disease, infertility, or complications in pregnancy if untreated. Early detection and treatment are crucial to prevent long-term health issues.
How soon after exposure can I get a positive result?
Antibodies may take 1–4 weeks to develop after infection, so results may not be positive immediately. If you suspect exposure, discuss timing with your provider.
Can I get this test if I’ve already been treated for chlamydia?
Yes, retesting may be recommended to confirm treatment success or if symptoms persist, though a negative result does not always mean the infection is fully cleared without medical confirmation.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy