The effect of digital cervical examination on group B streptococcal culture.
OBJECTIVE
We sought to evaluate whether group B streptococcus (GBS) detection is altered by the digital cervical examination.


METHODS
A total of 302 women undergoing the clinical GBS culture had a digital cervical examination and a repeated GBS culture. Statistical comparison of pre-post culture results were performed with kappa and McNemar tests.


RESULTS
The clinical prevalence of GBS was 19.5%. Discordant results were seen in 30/302 (9.9%) paired cultures (kappa = 0.68; 95% confidence interval, 0.568-0.783). An initially negative GBS culture result was positive on repeated testing in 13/243 (5.3%) pairs. Initially positive cultures were negative on repeated testing in 17/59 (28.8%) pairs. Patients with discordant results had similar characteristics as the remainder of the study group. Given the observed proportion of discordant results (9.9%), the study had 80% power to detect a 5% difference between discordant pairs.


CONCLUSIONS
Paired GBS cultures showed a good level of agreement. The 28.8% rate of positive cultures becoming negative is clinically concerning and warrants further study.
Knudtson
Eric J
EJ
Department of Obstetrics and Gynecology, the University of Oklahoma Health Sciences Center, Oklahoma City, USA.
Lorenz
Landon B
LB
Skaggs
Valerie J
VJ
Peck
Jennifer D
JD
Goodman
Jean R
JR
Elimian
Andrew A
AA
D000328:Adult; D002584:Cervix Uteri / Q000382:microbiology*; D015169:Colony Count, Microbial; D005260:Female; D006801:Humans; D015994:Incidence; D010808:Physical Examination; D011247:Pregnancy; D011263:Pregnancy Trimester, Third; D013290:Streptococcal Infections / Q000453:epidemiology; D013292:Streptococcus agalactiae / Q000302:isolation & purification*; D014626:Vaginal Smears; D055815:Young Adult