Aims
The purpose of this study was to determine the clinical significance of detecting microbial footprints of ureaplasmas in amniotic fluid (AF) using specific primers for the polymerase chain reaction (PCR) in patients presenting with cervical insufficiency.
Methods
Amniocentesis was performed in 58 patients with acute cervical insufficiency (cervical dilatation, ≥1.5 cm) and intact membranes, and without regular contractions (gestational age, 16–29 weeks). AF was cultured for aerobic and anaerobic bacteria as well as genital mycoplasmas. Ureaplasmas (Ureaplasma urealyticum and Ureaplasma parvum) were detected by PCR using specific primers. Patients were divided into three groups according to the results of AF culture and PCR for ureaplasmas: those with a negative AF culture and a negative PCR (n=44), those with a negative AF culture and a positive PCR (n = 10), and those with a positive AF culture regardless of PCR result (n=4).
Results
1) Ureaplasmas were detected by PCR in 19.0% (11/58) of patients, by culture in 5.2% (3/58), and by culture and/or PCR in 22.4% (13/58); 2) Among the 11 patients with a positive PCR for ureaplasmas, the AF culture was negative in 91% (10/11); 3) Patients with a negative AF culture and a positive PCR for ureaplasmas had a significantly higher median AF matrix metalloproteinase-8 (MMP-8) concentration and white blood cell (WBC) count than those with a negative AF culture and a negative PCR (P<0.001 and P<0.05, respectively); 4) Patients with a positive PCR for ureaplasmas but a negative AF culture had a higher rate of spontaneous preterm birth within two weeks of amniocentesis than those with a negative AF culture and a negative PCR (P<0.05 after adjusting for gestational age at amniocentesis); 5) Of the patients who delivered within two weeks of amniocentesis, those with a positive PCR for ureaplasmas and a negative AF culture had higher rates of histologic amnionitis and funisitis than those with a negative AF culture and a negative PCR (P<0.05 after adjusting for gestational age at amniocentesis, for each); (6) However, no significant differences in the intensity of the intra-amniotic inflammatory response and perinatal outcome were found between patients with a positive AF culture and those with a negative AF culture and a positive PCR.
Conclusions
1) Cultivation techniques for ureaplasmas did not detect most cases of intra-amniotic infection caused by these microorganisms (91% of cases with cervical insufficiency and microbial footprints for ureaplasmas in the amniotic cavity had a negative AF culture); 2) Patients with a negative AF culture and a positive PCR assay were at risk for intra-amniotic and fetal inflammation as well as spontaneous preterm birth.
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 mycoplasma, 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 3 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.
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