Objective: To determine the concordance between vaginal fluid Gram stains and pH obtained at speculum exam with similar stains and pH prepared from self-obtained vaginal swabs.
Methods: Using vaginal fluid Gram stain, 129 pregnant women were screened for bacterial vaginosis at 24 to 29 weeks' gestation. Two smears were collected from each woman during the same prenatal visit: the first was prepared from a self-obtained vaginal swab and the second from a physician-obtained speculum examination. Vaginal pH was recorded for each swab. Kappa coefficient was used to quantify agreement between the two sets of results.
Results: When compared with the physician-obtained smear, the ability of the self-obtained Gram stain to diagnose bacterial vaginosis had a sensitivity of 77%, specificity of 97%, positive predictive value of 71% and negative predictive value of 97%. There was substantial agreement (weighted kappa=0.82) between the two techniques in the ability to determine the grade of vaginal flora.
Conclusion: When compared with physician-obtained vaginal smears, self-obtained smears have substantial agreement in the diagnosis of bacterial vaginosis.