Common Sense Pathology

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Initial laboratory investigations

Choose laboratory tests based on the presumptive diagnosis from the patient history, the characteristic appearance of the ulcers, their distribution, and the associated findings.

The CDC recommends that all patients presenting with genital ulcers be tested for herpes simplex virus, syphilis and chancroid. These can be investigated individually (see details below) or via a multiplex PCR assay which detect all three pathogens on genital ulcer swabs (not currently widely available in South Africa ). 

Always test for HIV if a genital ulcer is present






Herpes simplex virus 

Genital ulcer swab or vesicle fluid in viral transport medium for virus isolation or PCR - the diagnostic technique of choice.

Wright's or Giemsa stain of genital ulcer scrapings for intranuclear inclusion or multi-nucleated giant cells.

Direct IF on smears

Serology may be useful in primary, but not recurrent, infection. 

Multiplex PCR to detect HSV, T. pallidum and H ducreyi

Syphilis (Treponema pallidum)

Serum for syphilis serology - RPR or VDRL 
plus confirmatory tests for specific antibody to T. pallidum are required i.e. syphilis IgG ± IgM or FTA or TPHA

Multiplex PCR to detect HSV, T. pallidum and H ducreyi

Chancroid (Haemophilus ducreyi)

Culture - the most sensitive and readily available method of establishing the diagnosis of Haemophilus ducreyi (chancroid) - 
P.S microscopy and culture for Haemophilus ducreyi needs to be specifically requested because it requires specialised transport media and specialised culture media in the laboratory.

Multiple PCR to detect HSV, T. pallidum and H. ducreyi

Lymphogranuloma venereum (Chlamydia trachomatis)

Direct IF - specific fluorescence with appropriate morphology may identify Chlamydia trachomatis.

PCR for Chlamydia trachomatis (LGV)

Granuloma inguinale (Calymmato- bacterium granulomatis)

Biopsy, aspirate of lesion for microscopy (incl. special stains � rapid diff) of smear or histology of biopsy for intracellular bacteria.
Culture is not used for diagnostic purposes. 


Swab of genital ulcer for microscopy and culture


Swab of genital ulcer for microscopy (wet mount)


Neoplastic ulcer
Fixed drug reaction
Behcet's syndrome
Trauma e.g. human bite
Crohn's disease

Lesion biopsy, if necessary

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