OBJECTIVE: The aim of this study was to determine the frequency, clinical characteristics
and significance of intra-amniotic inflammation in patients with preterm labour.
SUBJECTS AND METHODS: The study was conducted as a prospective, randomized
study. The patients were divided into 2 groups. The examined group consisted of patients
with singleton pregnancies and a diagnosis of preterm labor (PTL). The control group
consisted of patients with singleton pregnancies delivered at term. Comparison of numerical
and descriptive characteristics of the respondents was conducted between the experimental
and control group, as well as among members of the examined group compared to the
presence of abnormal colonization of the lower genital tract, the level of IL -6 in the amniotic
fluid and placenta and fetal membranes pathological findings. Amniotic fluid samples were
taken through a transabdominal amniocentesis, centrifuged, and were frozen at -70 ° C. The
concentration of interleukin-6 was measured by a colorimetric high-sensitive ELISA test
(R&D Systems) with a sensitivity of < 1pg/ml . Frequency of certain categories of descriptive
characteristics between groups were compared by χ2 test or Fisher 's test. Comparison of
numerical values of characteristics between the examined and control group was performed
by Student's t-test or Mann-Whitney U test when not fulfilled the requirement of normality
schedule. Comparison of numerical values between the three groups of subjects performed a
one-sided analysis of variance (one- way ANOVA) and Tukey post-hoc test. Probability level
of 5 % ( p < 0.05 ) is taken as the limit level of statistical significance.
RESULTS: Pregnant women in whom preterm delivery had occurred, more frequently had
burdened life history of desease and obstetric history. As well as the abnormal colonization
of the lower genital tract is significantly more frequent finding in the examined group, it was
also the presence of clinical chorioamnionitis, especially in cases with elevated amniotic fluid
levels of IL-6. There is a frequent association of clinical and histological chorioamnionitis in
the group of preterm labour. Preterm Premature Rupture of Membranes (PPROM) is
significantly more frequent in the examined group as well as the elevated values of uterine
artery RI. PPROM was significantly more often present in case of inflammatory changes in
the placenta and fetal membranes (chorioamnionitis). IUGR and a high uterine artery RI are
more often associated with pathological findings of placental vascular lesions. The majority
of deliveries were completed vaginally in both groups, but the perinatal outcome (Ap score)
was significantly worse in the group with PTL. AP score of 0-7 was more frequent in the
group of preterm deliveries with elevated levels of amniotic fluid IL-6. As well as the onset
of neuromorbidity, the overall neonatal morbidity was also more common in examined
group. The histopathological findings with the presence of inflammation and vascular lesions
were significantly more frequent in the experimental group, especially in cases of abnormal
genital tract colonization. Perinatal mortality was significantly higher in the experimental
group. Total perinatal mortality of the experimental group was significantly higher in the case
of elevated levels of IL- 6 in the amniotic fluid.
CONCLUSION: Preterm labor is a complex clinical syndrome, and intrauterine
inflammation plays an important role in its etiopathogenesis. In cases of PTL, burdened life
history is more frequent finding as well as the obstetric history of events that correlate with
the process of inflammation (irregularity of menstrual cycles, infertility, previous
miscarriages and premature births, bleeding in pregnancy, PIH and pre-eclampsia). Increased
levels of IL-6 in the amniotic fluid are often accompanied with PTL and can be a sensitive
biochemical marker of intrauterine inflammation and a good predictor of preterm delivery.
Basically, fetal/neonatal inflammatory response syndrome can be considered as a crucial
event in the high neuro and overall morbidity of preterm neonates. The high overall perinatal
mortality in cases with elevated amniotic fluid IL-6 levels in preterm deliveries suggests an
association of intra amniotic infection/inflammation and poor perinatal outcome