Amniotic Fluid Thrombin Activation in Intrauterine Infection and Preterm Parturition

Park, Kyo Hoon; Cho, Yong Kyoon

Abstract

OBJECTIVE
Disseminated intravascular coagulation (DIC) is a serious and life-threatening complication of amniotic fluid embolism and chorioamnionitis. DIC results from excessive thrombin activity leading to a consumptive coagulopathy. The mechanisms responsible for the increased availability of thrombin in intrauterine infection remain to be elucidated. The purpose of this study was to determine if thrombin activation in amniotic fluid, as measured by thrombin-antithrombin III (TAT) concentration, was associated with intrauterine infection and preterm delivery.
METHODS
A cross-sectional study included women who underwent transabdominal amniocentesis (n=129) in the following group: (1) mid-trimester (n=10) (2) preterm labor and intact membranes in the presence (n=17) or absence (n=72) of microbial invasion of the amniotic cavity, (3) term, not in labor and absence (n=30) of microbial invasion of the amniotic cavity. Intrauterine infection was defined as a positive amniotic fluid culture for microorganism. Thrombin was detected by assaying the thrombin-antithrombin III complex in amniotic fluid by means of sensitive and specific immunoassay (Enzygnost TAT micro; Behring Diagnostics Inc Westwood MA).
RESULTS
1) TAT complex was detected in all amniotic fluid samples and its concentration did not have a relation with gestational age. 2) The women with a positive amniotic fluid culture had a significantly higher median TAT complex concentration than those with a negative cultures (median, 168 micro gram/l; range, 23.1-288 vs median 80 micro gram/l; range, 10.7-507; p<0.05). 3) Multivariate analysis showed that amniotic fluid TAT complex was an independent predictor for preterm delivery (odd ratio 4.72, p<0.05) after correction for known confounding variables (i.e. gestational age, cervical dilatation at amniocentesis and positive amniotic fluid culture).
CONCLUSION
This study showed that TAT complex in amniotic fluid was elevated in women with preterm labor and intact membranes who had a intrauterine infection or were destined to deliver before term. Our findings support the hypothesis that the excess thrombin released during the course of intrauterine infection may play a role in the genesis of DIC in this condition.