What it measures
Chlamydia trachomatis, a common sexually transmitted bacterium. The lab looks for its genetic material with a nucleic acid amplification test (NAAT), which can find very small amounts. Many people with chlamydia have no symptoms.
Why people test it
- A routine check after a new partner, with or without symptoms.
- Investigating symptoms such as unusual discharge, pain when peeing or bleeding after sex.
- Checking after a partner has tested positive.
Typical range
There is no numeric range. The result is reported as detected or not detected (sometimes positive or negative). The report shows how that lab reports it and which sample was tested.
Finger-prick or vein?
This is not a blood test. It uses a urine sample or a swab, usually a vaginal swab, with throat or rectal swabs where needed. Kits that combine it with blood tests take the blood separately.
NHS sexual health services give a window period of up to 2 weeks for chlamydia: the time it can take for an infection to show on a test.