Laboratory Testing for Genital Herpes

Optimal Testing Approach

The European Centre for Disease Prevention and Control recommends PCR (nucleic acid amplification test) from swabs of active genital lesions as the initial test for diagnosing genital herpes, due to its superior detection rates and high sensitivity and specificity for HSV detection 1
PCR allows simultaneous detection and typing (HSV-1 vs HSV-2) in a single reaction tube, with results available in approximately 2 hours 1
For vesicular lesions, opening them with a sterile needle and collecting vesicular fluid with a cotton-wool or Dacron swab yields the highest detection rates (90% for viral culture, even higher for PCR) 1, 2, 3

For male patients with urethral involvement, cleaning the external urethral opening with saline-moistened swab and inserting swab 0.5-2 cm into the urethral meatus to collect exudates is recommended 2, 4
For female patients, collecting from cervical canal (2 cm depth) or vaginal wall using cotton-wool or Dacron swab on aluminum shaft is recommended 2, 4

Viral culture can be used as an alternative but has significantly lower sensitivity, particularly for ulcerative (70% detection) or crusting lesions (27% detection) 1
Antigen detection (immunofluorescence or enzyme immunoassay) can be employed for symptomatic patients but is less sensitive than PCR 1

Type-specific serologic testing based on glycoprotein G should be used for asymptomatic individuals or those with atypical presentations, with approximately 97% sensitivity and 98% specificity 1
Laboratory confirmation should always be sought because clinical diagnosis alone leads to both false positive and false negative results 2, 3

Do not rely on samples from crusted lesions as detection rates drop to 27% even with viral culture 1
Never rely on Tzanck smears or cytological examinations as they have low sensitivity and specificity 6
Do not use HSV-specific IgM testing to diagnose recent infection, as approximately one-third of patients with recurrent HSV-2 have IgM responses, making it a poor indicator 1

PCR samples tolerate less strict transportation conditions compared to viral culture 1
Viral culture samples require refrigeration during transport to maintain viability 1