Variability of vaginal pH determination by patients and clinicians

Daron Gale Ferris, Sean L. Francis, Eileen D. Dickman, Kimberly Miler-Miles, Jennifer L Waller, Nora McClendon

Research output: Contribution to journalArticlepeer-review

25 Scopus citations


Purpose: Measurement of intravaginal pH provides a reasonable assessment of vaginal health but is fraught with the potential for several sampling errors. The purposes of the study were to determine the variability of self-sampled vaginal pH among women using an inexpensive swab-based pH test compared with a clinician-obtained specimen, and variability of vaginal pH within 3 regions of the normal vagina. Methods: In this cross-sectional study, women obtained a vaginal specimen using a cotton-tip applicator, transferred it to pH paper, and interpreted the results. A clinician also blindly interpreted these tests. Thereafter, a clinician obtained 3 swab specimens from the proximal, middle, and distal vagina for pH testing. Results were compared using Wilcoxon signed rank test, interclass correlation coefficients, Bland-Altman plots, and mixed-model analysis of variance. Results: Interclass correlation coefficients were moderately high comparing subjects with clinician for the swab-based pH test (0.74). Subjects' swab pH values (4.5) were significantly lower than clinicians' pH values (4.7, P = .0001). Intravaginal pH did not vary between the 3 anatomic locations. Conclusions: Self-sampled intravaginal pH interpretations vary slightly compared with clinician-obtained specimens. Because swab pH sampling does not detect an intravaginal pH gradient in normal women, self-sampling technique may vary considerably without affecting outcomes. Our findings support self-sampling for vaginal pH before using over-the-counter products for presumed vaginitis.

Original languageEnglish (US)
Pages (from-to)368-373
Number of pages6
JournalJournal of the American Board of Family Medicine
Issue number4
StatePublished - 2006

ASJC Scopus subject areas

  • Public Health, Environmental and Occupational Health
  • Family Practice


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