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10: The frequency and clinical significance of intra-amniotic inflammation in women with preterm labor symptoms without cervical change

      Objective

      Preterm labor has been traditionally defined as regular uterine contractions with progressive cervical change, and there have been strong evidences on the relationship between intra-amniotic infection and/or inflammation and adverse pregnancy outcomes in preterm labor. However there is a paucity of information regarding the clinical significance of intra-amniotic infection and/or inflammation in patients with regular uterine contractions without cervical change. The objective of this study was to determine the frequency and clinical significance of IAI in patients with regular uterine contractions and intact membranes without cervical change in preterm gestations.

      Study Design

      Amniocentesis was performed in 127 patients with regular uterine contractions and intact membranes with cervical dilatation of ≤1 cm but without cervical change. Amniotic fluid (AF) was cultured for aerobic and anaerobic bacteria and genital mycoplasmas and assayed for matrix metalloproteinase-8 (MMP-8). Intra-amniotic inflammation was defined as an elevated AF MMP-8 concentration (>23 ng/mL). Nonparametric tests and survival methods were used for statistical analysis.

      Results

      The frequency of intra-amniotic inflammation (IAI) was 11.8% (15/127) in patients with regular uterine contractions without cervical change. Patients with IAI had higher rate of delivery within 7 days after amniocentesis (64.3% vs. 13.9%, P<0.001) and preterm delivery before 37 weeks of gestation (92.9% vs. 35.2%, P<0.001) than those without IAI. Patients with IAI had significantly shorter amniocentesis-to-delivery interval than those without IAI by survival analysis (P=0.017) and this difference remained significant after adjustment for gestational age at amniocentesis.

      Conclusions

      Intra-amniotic inflammation is present in approximately 12% of patients with regular uterine contractions without cervical change and is a significant risk factor for impending preterm delivery.