Chlamydia Antibody Test (Qualitative, Serum or Plasma)
This test detects antibodies to *Chlamydia trachomatis*, a common bacterial infection that can affect the reproductive system, eyes, or throat. It helps identify past or current infection when symptoms aren’t present.
["This test checks for immunity or exposure to chlamydia, often used in routine screening or after potential exposure."]
Key facts at a glance
- LOINC
- 45103-9
- Short code
- CHLAGA
- Synonyms
- Chlamydia Ag Anal Ql IF
- Category
- chemistry
- Sample
- serum
- Container
- Sterile Dacron or rayon swab in viral transport medium (VTM) or chlamydia transport medium; sterile screw-capped container
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 14–99 years
- Method
- Direct Immunofluorescence Assay (DFA)
- CPT
- 87320
- SNOMED
- 441884004
- Specimen volume
- Anal swab specimen collected by inserting a sterile swab 2-3 cm into the anal canal and rotating against the rectal wall for 10-30 seconds
- Stability
- Room temperature: 1 hour; Refrigerated (2-8°C): 24-48 hours; Frozen (-70°C or below): 1 week. Transport to laboratory as soon as possible after collection.
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 24–72 hours
- Order
- routine
Why This Test Is Done
Doctors may recommend this test if you have symptoms like unusual discharge, pain during urination, or bleeding between periods. It’s also commonly used in annual sexually transmitted infection (STI) screenings, especially for sexually active individuals. Some healthcare providers may suggest it if you’ve had unprotected sex with multiple partners or if you’ve been exposed to chlamydia.
What to Expect Before the Test
No special preparation is needed. You’ll provide a blood sample from a vein in your arm, similar to other blood tests. If you’re tested for chlamydia antibodies in urine, you may be asked to collect a midstream urine sample at home or in a clinic.
What the Test Results Mean
A positive result means your body has produced antibodies against chlamydia, suggesting past infection. A negative result means no detectable antibodies were found at this time. Follow-up testing or treatment may be recommended based on your symptoms and medical history.
Possible Side Effects
Most people experience no side effects from a blood draw. You might feel slight bruising, tenderness, or swelling at the injection site, which usually goes away within a few days. If you experience severe pain or bleeding, contact your healthcare provider.
Reference range
Negative: No Chlamydia sp. antigen detected. Positive: Chlamydia sp. antigen detected, indicating active infection.N/A
Patient should refrain from using rectal medications, enemas, or douches for at least 24 hours prior to specimen collection. Avoid recent antibiotic use if possible, as it may affect test sensitivity.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
Chlamydia Antibody Screen
Frequently asked questions
This test is primarily used to diagnose past or recent chlamydia infection, even when symptoms are absent. It’s not a direct test for live bacteria, so it can’t confirm active infection without additional testing (like a nucleic acid amplification test). Antibody tests are useful for screening, but they may not detect recent infections (antibodies take time to develop).
A positive result indicates your body has likely been exposed to chlamydia in the past. You may need further testing to determine if the infection is still active. Your healthcare provider will discuss next steps, which may include treatment for past infection or additional testing for current infection. Untreated chlamydia can lead to serious health issues, including pelvic inflammatory disease or infertility.
Yes, if your test is positive, your healthcare provider will likely prescribe antibiotics to treat the infection. Treatment is usually effective, but you may need to return for follow-up testing to confirm the infection is cleared.
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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