Question
How well do cervical Pap smears and vaginal cultures perform compared to the Nugent Gram stain scoring method for the diagnosis of bacterial vaginosis (BV) in women attending an Obstetrics and Gynecology clinic for routine genital examinations?

Design
This article describes a prospective, blinded study to determine the performances of the Pap stained cervical smear and of vaginal culture in the diagnosis of BV, with the vaginal Gram stain used as the diagnostic standard.

Participants
Two hundred forty-five women who were referred to the Obstetrics and Gynecology clinic of a hospital in Afyon, Turkey, for routine genital examinations were tested. Women who were pregnant or had vaginal bleeding were excluded. The mean age was 41.1 years (range = 19 to 77 years).

Description of Tests and Diagnostic Standard
Standard Pap smears collected with an endocervical brush were evaluated under the Bethesda system guidelines. Smears were considered positive for BV if there was a filmy background of small coccobacilli, individual squamous cells with a layer of coccobacilli along the margins of the cell membranes, and conspicuous absence of lactobacilli. Vaginal swabs were cultured on 5% blood agar, eosin methylene blue agar and Sabouraud dextrose agar and evaluated following 24 to 48 h incubation at 37oC in microaerophilic conditions. Growth of G. vaginalis was positive for BV. Standard Gram stains were prepared from vaginal swab specimens taken from the posterior fornix and evaluated according to the Nugent criteria (0 to 10 point scoring system). Smears with a score of 7 or greater were positive for BV.

Main Outcome Measures
The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the Pap smear and of the vaginal culture for the diagnosis of BV as determined by the Nugent Gram stain score were calculated.

Main Results
Seventy-two (29.4%) of the 245 women were positive for BV by the Nugent Gram stain method. The performance of the cervical Pap smear and the vaginal culture compared to the Gram stain for the diagnosis of BV is shown in the table.

Authors’ Conclusions
Although the cervical Pap smear and the vaginal culture were less sensitive than the Nugent Gram stain score for screening BV, the high specificity of each of these methods provides an adequate diagnostic criteria when the result is positive.

Source of funding:  None given

For correspondence:  Çiðdem Tokyol, Dumlupinar mah. 2. Cad, No: 26/11 03200, Afyon, Turkey.

ctokyol@hotmail.com.