title: Optimal methods for collecting and storing vaginal specimens for prostate-specific antigen testing in research studies.
abstract: BACKGROUND
  Prostate-specific antigen (PSA) detected in vaginal fluid can be used in studies of HIV/sexually transmitted infection (STI) and pregnancy prevention as an alternative to relying on participant reports of exposure to semen. Optimal methods for collecting and storing specimens for this testing have not been determined.
  
  
  METHODS
  We conducted a controlled, in vitro experiment of 550 specimens spiked with semen to determine the effects of swab type (five types), storage conditions of the swabs (room temperature with or without desiccant or at -80°C without desiccant) and time from collection to testing (seven intervals over the course of 12 months) on the identification of PSA. We performed factorial analysis of variance to identify factors influencing PSA detection.
  
  
  RESULTS
  Concentrations of PSA detected in the swabs declined with time of storage over the 1-year experiment (p<.01). The 1-mL, rayon-tipped swab stored immediately at -80°C following collection performed best.
  
  
  CONCLUSIONS
  If immediate testing or freezer storage is not feasible, investigators should use a swab with 1-mL capacity with processing and testing as soon as possible after specimen collection.
authors.affiliation: Division of Reproductive Health, National Center for Chronic Disease Prevention and Health Promotion, Centers for Disease Control and Prevention, 4770 Buford Highway, Mail Stop K-34, Atlanta, GA 30341-3724, USA. mgallo@cdc.gov
authors.forename: Maria F
authors.initials: MF
authors.lastname: Gallo
authors.forename: Margaret C
authors.initials: MC
authors.lastname: Snead
authors.forename: Carolyn M
authors.initials: CM
authors.lastname: Black
authors.forename: Teresa M
authors.initials: TM
authors.lastname: Brown
authors.forename: Athena P
authors.initials: AP
authors.lastname: Kourtis
authors.forename: Denise J
authors.initials: DJ
authors.lastname: Jamieson
authors.forename: Marion
authors.initials: M
authors.lastname: Carter
authors.forename: Ana
authors.initials: A
authors.lastname: Penman-Aguilar
authors.forename: Maurizio
authors.initials: M
authors.lastname: Macaluso
mesh_terms: D015415:Biomarkers / Q000032:analysis / Q000378:metabolism; D035843:Biomedical Research / Q000379:methods; D002482:Cellulose / Q000737:chemistry; D015925:Cryopreservation; D005163:Factor Analysis, Statistical; D005260:Female; D005554:Forensic Medicine / Q000379:methods; D049429:Forensic Pathology / Q000379:methods; D006801:Humans; D058427:Hygroscopic Agents / Q000737:chemistry; D057230:Limit of Detection; D008297:Male; D008422:Materials Testing; D017430:Prostate-Specific Antigen / Q000032:analysis* / Q000378:metabolism; D011933:Reagent Kits, Diagnostic; D015203:Reproducibility of Results; D012661:Semen / Q000378:metabolism; D013997:Time Factors; D014021:Tissue Preservation; D014626:Vaginal Smears / Q000295:instrumentation
chemical_list: D015415:Biomarkers; D058427:Hygroscopic Agents; D011933:Reagent Kits, Diagnostic; D002482:Cellulose; C012024:rayon, purified; D017430:Prostate-Specific Antigen