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pubmed:otherAbstract |
PIP: Objective markers of exposure to semen provide a more valid assessment of condom failure and failure to use condoms than self-reports. The present study evaluated three of the assays commonly used in forensic medicine for detecting semen exposure: acid phosphatase (AP) activity, prostate specific antigen (PSA), and the human seminal plasma antigen (MHS-5). 20 US women were intravaginally inoculated with 6 measured, increasingly larger amounts of their partners' semen. Vaginal fluid was collected with swabs by study participants and tested for the three markers. Before semen inoculation, PSA levels were consistently low (median, 0.11 ng/ml; range, 0-1.25 ng/ml) while those of AP were highly variable (median, 13.4 U/l; range, 0-350 U/l); all preinoculation samples were negative for MHS-5. The median PSA concentration increased consistently with increasing volumes of semen, while median AP and MHS-5 levels showed an inconsistent pattern. All 120 swabs obtained after intravaginal inoculation with semen were positive for PSA, 64 (55%) were positive for AP, and 14 (12%) were positive for MHS-5. These findings indicate that self-sampling of vaginal secretions followed by the PSA immunoassay represents a simple, accurate marker of semen exposure. Because the PSA assay is available in most hospital laboratories for prostate cancer screening, the methodology used in the present study is suitable for widespread application.
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