The frequency of microbial invasion of the amniotic cavity and histologic chorioamnionitis in women at term with intact membranes in the presence or absence of labor

OBJECTIVE: The amniotic cavity is normally sterile for bacteria. However, experimental evidence indicates that regular uterine contractions exert a suction-like effect whereby vaginal fluid ascends into the uterine cavity with contractions (demonstrated by sonohysterography contrast media). Consequently, this study was conducted to determine whether the presence and progress of labor are associated with an increased risk of microbial invasion of the amniotic cavity (MIAC), intraamniotic inflammation, and histologic chorioamnionitis in women with term pregnancies with intact membranes. STUDY DESIGN: Amniotic fluid (AF) was obtained from term singleton pregnant women with intact membranes at the time of cesarean delivery. AF was cultured for aerobic and anaerobic bacteria and genital mycoplasmas, and white blood cell (WBC) count was determined. Patients were divided into 3 groups according to the presence or absence of labor and the progress of labor. Nonparametric statistics were used for analysis.