What laboratory tests should be included in routine sexually transmitted disease screening?

Routine STD Screening Laboratory Tests

All sexually active individuals should be screened with nucleic acid amplification tests (NAATs) for chlamydia and gonorrhea, serologic testing for syphilis (using both treponemal and non-treponemal tests), and HIV antibody/antigen testing. 1, 2

Core Testing Panel for All Sexually Active Patients

Essential Tests

• Chlamydia trachomatis NAAT - Preferred specimen is vaginal swab for women or first-void urine for men 1
• Neisseria gonorrhoeae NAAT - Same specimen types as chlamydia; simultaneous testing is optimal 1, 2
• Syphilis serology - Use reverse algorithm with treponemal-specific test (EIA/chemiluminescence) first, followed by RPR confirmation 1, 2
• HIV testing - Fourth-generation antibody/antigen combination test with reflex confirmatory testing 2, 3

Additional Tests Based on Sex and Risk

• Trichomonas vaginalis NAAT - For all sexually active women, especially those under 25 or with multiple partners 1, 2
• Hepatitis B surface antigen (HBsAg) - For all pregnant women and high-risk individuals 2, 3
• Hepatitis C antibody - For persons who inject drugs (even once) and MSM with high-risk behaviors 2, 3

Population-Specific Screening Requirements

Women Under 25 Years

• Annual screening mandatory for chlamydia and gonorrhea regardless of symptoms 1, 2
• Vaginal swab NAAT is the preferred specimen collection method 1, 2
• Add trichomoniasis testing if multiple partners or history of STIs 2

Men Who Have Sex with Men (MSM)

• Test all three anatomic sites - urogenital, rectal, and oropharyngeal for chlamydia and gonorrhea based on reported sexual practices 1, 2, 3
• Rectal and pharyngeal infections are frequently asymptomatic and will be missed with urogenital-only testing 1, 2
• Syphilis screening at minimum annually, with every 3-6 months for those with multiple/anonymous partners, methamphetamine use, or sex during drug use 1, 2

Pregnant Women - First Prenatal Visit

• Universal screening required for HIV, syphilis, and hepatitis B 2, 3
• Chlamydia and gonorrhea if under 25 years or at increased risk 2, 3
• Third trimester repeat syphilis testing for high-risk women 2, 3
• Group B streptococcus screening at 35-37 weeks using both vaginal and rectal swabs 1, 3

HIV-Positive Individuals

• Screen every 3-6 months for all bacterial STIs (chlamydia, gonorrhea, syphilis, trichomoniasis) due to increased HIV transmission risk when co-infected 2, 3
• Annual syphilis screening at minimum, more frequently with ongoing high-risk behaviors 2

Specimen Collection Sites and Methods

Optimal Specimen Types

• Women: Vaginal swab NAAT has superior sensitivity compared to cervical specimens 1, 2
• Men: First-void urine or urethral swab for urogenital testing 1
• MSM: Site-specific swabs (rectal, oropharyngeal) based on sexual exposure history 1, 2

Critical Testing Notes

• NAATs have substantially higher sensitivity than culture for chlamydia detection 1
• Detection of rectal or pharyngeal gonorrhea requires culture if NAAT is not validated for these sites 1
• Wet mount microscopy for trichomoniasis misses 30-40% of infections; NAAT should be used instead 2

Genital Lesion Evaluation

When genital lesions are present, all patients require three specific tests regardless of lesion appearance 1:

• Serologic test for syphilis (mandatory) 1, 3
• HSV testing via NAAT (preferred over culture for highest sensitivity and typing) 3
• HIV screening (inflammatory epithelium enhances HIV transmission risk) 3

Post-Treatment and Follow-Up Testing

Mandatory Retesting

• All patients treated for chlamydia or gonorrhea must be retested at 3 months after treatment, regardless of whether partners were treated 1, 2
• Reinfection rates reach 25-40% within 3 months of treatment 1, 2

Screening Frequency for High-Risk Populations

• Every 3-6 months for HIV-infected individuals with multiple partners, unprotected intercourse, or methamphetamine use 2, 3
• Every 3-6 months for MSM with multiple/anonymous partners or drug use during sex 1, 2

Common Pitfalls to Avoid

• Never rely on clinical symptoms alone - most STDs are asymptomatic in 25-40% of cases 1
• Do not skip extragenital testing in MSM - rectal and pharyngeal infections are frequently missed with urogenital-only testing 1, 2
• Do not use wet mount for trichomoniasis diagnosis - NAAT is required for adequate sensitivity 2
• Do not screen asymptomatic patients for HSV - there is no evidence that treating asymptomatic HSV improves outcomes 2
• Never discharge an infant without determining mother's syphilis status at least once during pregnancy 2

Partner Management and Reporting

• All sexual partners from the past 60 days must be notified and treated presumptively before test results when indicated 2, 3
• Syphilis, gonorrhea, chlamydia, and HIV are reportable in all states 1, 2, 3
• Most treatment "failures" represent reinfection from untreated partners 1, 3