Variability of vaginal pH determination by patients and clinicians

J Am Board Fam Med. Jul-Aug 2006;19(4):368-73. doi: 10.3122/jabfm.19.4.368.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Attitude to Health
  • Cross-Sectional Studies
  • Female
  • Health Personnel*
  • Humans
  • Hydrogen-Ion Concentration*
  • Patients*
  • Self Care
  • Self Efficacy
  • Time Factors
  • Vagina / physiology*
  • Vaginitis / diagnosis
  • Young Adult