Which laboratory tests are essential for the diagnosis of STIs in a primary care setting?

Guideline-aligned answer with reasoning, red flags and references. Clinically reviewed by Dr Kola Tytler MBBS CertHE MBA MRCGP.

Posted: 16 August 2025 Guideline-Aligned (High Confidence) Clinically Reviewed
Dr Kola Tytler MBBS CertHE MBA MRCGPClinical Lead • iatroX

In a primary care setting, essential laboratory tests for the diagnosis of sexually transmitted infections (STIs) include:

  • Chlamydia and Gonorrhoea testing: Nucleic acid amplification tests (NAATs) on urine samples or swabs from relevant sites (genital, rectal, or throat) are standard for detecting these infections ,.
  • Syphilis testing: A full syphilis screen usually involves a combination of treponemal tests (such as enzyme immunoassay [EIA] or chemiluminescent assay [CLIA]) and non-treponemal tests (such as rapid plasma reagin [RPR] or Venereal Disease Research Laboratory [VDRL] test) to confirm diagnosis and stage the disease .
  • Herpes simplex virus (HSV) testing: Virology swabs from active lesions (genital, extragenital, or oral) for PCR testing are recommended if lesions are present to exclude herpes simplex infection .
  • Hepatitis B and C testing: Serological tests for hepatitis B surface antigen and hepatitis C antibody, with reflex PCR testing for hepatitis C RNA if antibody positive, are essential for people at risk .
  • HIV testing: HIV antibody/antigen combination tests are recommended, with rapid or laboratory-based assays available; testing should be offered routinely to those at risk .

Offering a full sexual health screen including HIV testing alongside syphilis and other STI tests is recommended because individuals at risk for one STI are often at risk for others ,.

Educational content only. Always verify information and use clinical judgement.