Meeting paper
SMFM paper
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

Presented at the 28th Annual Clinical Meeting of the Society for Maternal-Fetal Medicine, Dallas, TX, Jan. 28-Feb. 2, 2008.
https://doi.org/10.1016/j.ajog.2008.06.040Get rights and content

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.

Results

Results included: (1) a total of 884 pregnant women were enrolled and divided into 3 groups: group 1, not in labor (n = 775); group 2, in early labor (cervical dilatation less than 4 cm) (n = 86); and group 3, in active labor (cervical dilatation 4 cm or greater) (n = 23); (2) the frequency of MIAC was 1% (6 of 775) in women not in labor, 3.5% (3 of 86) in patients with early labor, and 13% (3 of 23) in patients with active labor; and (3) the median AF WBC count and the frequency of histologic chorioamnionitis were also higher in the presence of labor than in the absence of labor.

Conclusion

We came to the following conclusions: (1) labor is associated with an increased risk of MIAC, a higher median AF WBC count, and histologic chorioamnionitis in term pregnancy with intact membranes; (2) the more advanced the cervical dilatation, the greater the risk of MIAC, a higher median AF WBC count, and histologic chorioamnionitis; and (3) in contrast, fetal inflammation (funisitis) did not increase with the presence of labor or as a function of cervical dilatation. We propose that labor predisposes to MIAC, a higher median AF WBC count, and histologic chorioamnionitis.

Section snippets

Study design

A retrospective analysis was conducted on pregnant women at term with intact membranes who delivered singleton neonates (gestational age 37 weeks or longer) at Seoul National University Hospital and who had AF retrieved at the time of cesarean delivery. This criterion (inclusion of patients whose AF was obtained at the time of cesarean delivery) was used to preserve a meaningful temporal relationship between the results of AF studies and the histological findings of the placenta and umbilical

Results

A total of 884 singleton pregnant women were enrolled and divided into 3 groups according to the presence or absence of labor and the progress of labor: group 1, women not in labor (n = 775); group 2, women in early labor (cervical dilatation less than 4 cm) (n = 86); group 3, women in active labor (cervical dilatation 4 cm or greater) (n = 23).

The clinical indications for cesarean deliveries included previous cesarean section (n = 632), malpresentation (n = 118), placenta previa (n = 30),

Comment

The principal findings of this study were: (1) MIAC and histologic chorioamnionitis is present in 1% and 6% of patients in term pregnancy with intact membranes, respectively; (2) the presence of labor at term is associated with an increased risk of MIAC and a higher median AF WBC count; (3) patients who had entered the active phase of labor at term with intact membranes had a higher rate of MIAC and histologic chorioamnionitis than those with a cervical dilatation of less than 4 cm; and (4)

References (33)

Cited by (0)

This study was supported by grant R01-2006-000-10607-0 from the Korea Science and Engineering Foundation, funded by the Korean government (Ministry of Science and Technology).

Cite this article as: Seong HS, Lee SE, Kang JH, et al. 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. Am J Obstet Gynecol 2008;199:375.e1-375.e5.

View full text