Related Experiment Video
Updated: Aug 7, 2026
The Examination of Peroxidase-Positive Leukocytes in Semen
Published on: January 19, 2024
Prostate-specific antigen to ascertain reliability of self-reported coital exposure to semen
Maria F Gallo1, Frieda M Behets, Markus J Steiner
1Family Health International (FHI), Research Triangle Park, North Carolina, USA. mgallo@cdc.gov
Objective:
The objective of this study was to assess the validity of women's reports of recent unprotected sex by testing for prostate-specific antigen (PSA) in vaginal samples.
Study Design:
The authors conducted prospective research with 332 female sex workers attending 2 public dispensaries in Madagascar.
Results:
Among women who reported no sex or protected sex only within the past 48 hours, 21% and 39%, respectively, tested positive for PSA. Among those testing positive for PSA, no differences in PSA concentrations were found among those reporting no sex, protected sex only, or at least one unprotected act.
Conclusions:
The substantial disagreement between self-reports and measurement of a biologic marker of semen exposure in vaginal specimens substantiates that self-reports of sexual behavior cannot be assumed to be valid measures. Future sexually transmitted infection/HIV and pregnancy prevention studies should confirm the validity of self-reports or use end points that do not rely on self-reported data.
