The frequency and significance of intraamniotic inflammation in patients with cervical insufficiency.

OBJECTIVE: The purpose of this study was to determine the frequency and clinical significance of intraamniotic inflammation in patients with acute cervical insufficiency.

STUDY DESIGN: Amniocentesis was performed in 52 patients with acute cervical insufficiency (cervical dilation, > or =1.5 cm) and intact membranes and without regular uterine contractions (gestational age, 17-29 weeks). Amniotic fluid (AF) was cultured for aerobic and anaerobic bacteria and genital mycoplasmas and assayed for matrix metalloproteinase-8. Intraamniotic inflammation was defined as an elevated AF matrix metalloproteinase-8 concentration (>23 ng/mL). Nonparametric statistics and survival techniques were used for analysis.

RESULTS: The prevalence of intraamniotic inflammation was 81% (42/52); the prevalence of a positive AF culture was 8% (4/52). Intraamniotic inflammation was present in all cases with a positive AF culture. Preterm delivery within 7 days occurred in 50% of cases (19/38), and delivery before 34 weeks of gestation occurred in 84% of cases (32/38) with intraamniotic inflammation but without AF infection. Fifty-five percent of newborn infants (21/38) who were born to mothers with intraamniotic inflammation but without AF infection died immediately after birth (<1 day). The amniocentesis-to-delivery interval was shorter in patients with intraamniotic inflammation than in those without inflammation (P < .05). There were no differences in the interval-to-delivery or the rate of adverse outcome between patients with intraamniotic inflammation and a negative culture and patients with proven AF infection.

CONCLUSION: Intraamniotic inflammation, regardless of AF culture result, is present in approximately 80% of patients with acute cervical insufficiency and is a risk factor for impending preterm delivery and adverse outcomes.