title: A quantitative glycogen assay to verify use of self-administered vaginal swabs.
abstract: BACKGROUND
  Self-administered swabs are used to sample vaginal contents for a variety of clinical purposes including detection of sexually transmitted infections, condom breakage, and vaginal product use. The goal of this study was to determine whether a quantitative glycogen assay can be used to assess whether a swab has been exposed to the vagina to assure study compliance.
  
  
  METHODS
  Buccal, skin, or vaginal samples were tested to determine whether a commercial quantitative glycogen assay can differentiate vaginal specimens. In addition, archived remnant de-identified vaginal swabs from clinical trials were tested. Periodic acid-Schiff stain was used to identify glycogen-positive cells as a confirmation test.
  
  
  RESULTS
  Glycogen concentrations in eluates of vaginal swabs from reproductive-aged women were significantly higher than those from unused swabs (mean ± SE, 964 ± 135 μg/mL vs. 14.7 ± 2.5 μg/mL, P < 0.001) and swabs exposed to buccal and finger/hand epithelia (40.3 ± 4.8 and 18.5 ± 5.4 μg/mL, P < 0.001). Glycogen concentrations were lower and more variable in vaginal swabs from older perimenopausal/menopausal women (mean ± SE, 235 ± 123, P < 0.01). Semen and sample storage longer than 1 year did not affect glycogen detection. Using a cutoff of 100 μg/mL of glycogen, 30 of 30 vaginal swabs from reproductive-aged women versus 0 of 28 control swabs were positive, for an assay sensitivity of 1 (95% confidence interval, 0.86-1) and specificity of 1 (95% confidence interval, 0.85-1). Periodic acid-Schiff stain correlated with soluble glycogen results but was less specific.
  
  
  CONCLUSIONS
  The quantitative glycogen assay provides a simple and inexpensive method to validate the use of self-administered swabs for sampling vaginal contents in clinical studies.
authors.affiliation: Division of Reproductive Biology, Department of Obstetrics and Gynecology, Boston University School of Medicine, Boston 02118, MA. Deborah.Anderson@BMC.org
authors.forename: Deborah J
authors.initials: DJ
authors.lastname: Anderson
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Politch
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Pudney
authors.forename: Cecilia I
authors.initials: CI
authors.lastname: Marquez
authors.forename: Margaret C
authors.initials: MC
authors.lastname: Snead
authors.forename: Christine
authors.initials: C
authors.lastname: Mauck
mesh_terms: D000328:Adult; D000367:Age Factors; D005260:Female; D006003:Glycogen / Q000032:analysis*; D006225:Hand / Q000382:microbiology*; D006801:Humans; D009061:Mouth Mucosa / Q000382:microbiology*; D011237:Predictive Value of Tests; D011933:Reagent Kits, Diagnostic / Q000706:statistics & numerical data; D012680:Sensitivity and Specificity; D012749:Sexually Transmitted Diseases / Q000175:diagnosis / Q000382:microbiology*; D013048:Specimen Handling; D014621:Vagina / Q000382:microbiology*; D014626:Vaginal Smears / Q000379:methods*
chemical_list: D011933:Reagent Kits, Diagnostic; D006003:Glycogen