Approach Considerations
Due to higher risks, testing for LGV is recommended for all men who have sex with men (MSM) with a C. trachomatis positive anorectal sample. [3]
Laboratory Studies
Initial laboratory analysis may reveal mild leukocytosis.
These nonspecific results do not aid the clinician in the diagnosis of lymphogranuloma venereum (LGV).
Previously, the Frei test was the only method available to identify a chlamydial infection. The Frei intradermal test is only of historical interest. The test was based on a positive hypersensitivity to an intradermal standardized antigen, lymphogranuloma venereum, which indicated past or present chlamydial infection. The Frei test would become positive 2-8 weeks after infection. Unfortunately, the Frei antigen is common to all chlamydial species and is not specific to LGV. Commercial manufacturing of Frei antigen was discontinued in 1974.
Complement fixation (CF) is more sensitive than the Frei skin test, but it has some cross-reactivity with other chlamydial species. CF sensitivity is 80% for LGV. A test titer of 1:16 is strongly suggestive of LGV and a titer of >1:64 indicates active LGV. A 4-fold rise or fall in titer further supports the diagnosis.
The microimmunofluorescence test for the L-type serovar of C trachomatis is a more sensitive and specific test. A titer greater or equal to 1:512 is diagnostic. However, availability of this test is limited.
Application of nucleic acid amplification techniques have been used to confirm the diagnosis with much greater certainty. Polymerase chain reaction (PCR) assays have been used for diagnosis recently in several outbreaks. PCR is a far superior test but has limited availability to reference laboratories. Multiplexed real-time PCR assays have been developed for the rapid detection of Chlamydia trachomatis and specific serovars. [13] As these tests are refined and approved for widespread use, they will speed detection and diagnosis.
Dermatopathology is not pathognomonic for LGV, and cytology using Giemsa stain or iodine stain fails to provide a high percentage of diagnoses.
Definitive diagnosis may be made by aspiration of the bubo and growth of the aspirated material in cell culture. C trachomatis can be cultured in as many as 30% of cases.
Arnold et al emphasize the need to screen for LGV in routine anocolonic biopsies to ensure timely treatment, avoid misdiagnosis, and prevent STI transmission. [14]
Imaging Studies
CT scan may be useful if retroperitoneal adenitis or intraabdominal abscess is suspected, but it is rarely necessary in the ED.
Lymphography does not outline buboes, but it may demonstrate the extent of lymph node involvement. This test is seldom ordered in the ED.
A barium enema may reveal the characteristic elongated stricture in rectal LGV.
Other Tests
Venereal Disease Research Laboratory (VDRL) test or rapid plasma reagin (RPR), PCR assays for Haemophilus ducreyi and HSV-2, and HIV antibodies should be considered because patients with LGV may be co-infected with other sexually transmitted diseases.
Procedures
A bubo may be aspirated to speed healing, but this is not necessary for culture since other diagnostic methods are more sensitive and specific.
