Diagnostic Testing for Lymphogranuloma Venereum (LGV)
The diagnosis of LGV requires nucleic acid amplification testing (NAAT) for Chlamydia trachomatis followed by LGV-specific discriminatory testing to identify L1, L2, or L3 serovars, combined with serological testing when available. 1, 2
Primary Diagnostic Approach
Step 1: Initial NAAT Testing
- Obtain specimens from the site of infection (genital ulcer, rectal swab for proctitis, or urethral/cervical swab) and test using standard commercial NAAT platforms for Chlamydia trachomatis 1, 3
- Standard NAATs will detect C. trachomatis but cannot distinguish LGV serovars (L1-L3) from non-LGV serovars 4
- For men who have sex with men (MSM) with proctitis symptoms, rectal swabs are the primary specimen 3, 2
Step 2: LGV-Specific Confirmatory Testing
- Any positive C. trachomatis NAAT should be confirmed with an LGV discriminatory NAAT to identify L1, L2, or L3 serovars 2
- These discriminatory tests are typically available only through reference laboratories or public health laboratories 3, 5
- Critical caveat: LGV-specific testing is not widely available in most clinical settings 5
Serological Testing
Complement Fixation (CF) Test
- CF titers ≥64 with appropriate clinical presentation suggest LGV, with sensitivity of 80% at 2 weeks 4, 1
Microimmunofluorescence (MIF) Test
- MIF titers ≥256 with appropriate clinical presentation suggest LGV 4, 1
- Serological testing provides supportive evidence but should not be used as the sole diagnostic method 4
Clinical Diagnosis When Testing Unavailable
When LGV-specific confirmatory testing is not available, diagnosis is made by exclusion of other causes combined with clinical presentation 4:
- Tender unilateral inguinal/femoral lymphadenopathy in heterosexual men 4, 1
- Proctocolitis or proctitis in MSM or women, with symptoms resembling inflammatory bowel disease 1, 3
- History of self-limited genital ulcer at inoculation site (often no longer present when patient seeks care) 4, 1
Key Clinical Pitfall
- Approximately 25% of anorectal LGV infections in MSM are asymptomatic, so testing should be performed even without symptoms in high-risk populations 2
- The ratio of genital to anorectal LGV infections in MSM is 1:15, making rectal testing critical 2
Practical Algorithm
Patient with proctitis/proctocolitis or inguinal lymphadenopathy: Obtain NAAT for C. trachomatis from appropriate site 3
If NAAT positive: Send specimen for LGV discriminatory testing if available 2
If discriminatory testing unavailable: Obtain serological testing (CF or MIF) and treat empirically for LGV if clinical presentation is consistent 3, 5
All patients with rectal chlamydial infection AND signs/symptoms of proctitis should be tested for LGV or treated empirically 3