Procoagulant properties of amniotic fluid

Thromboplastin Activity in Amniotic Fluid

“…This is in accordance with some recent clinical studies from the United States reporting that legally induced abor tions between the 14th and 23rd weeks of gestation can be complicated with amniotic fluid embolism, of which approximately 60-70% developed disseminated intravascular coagulation [3], Our results, however, are in contrast to the thrombogenic effect of am niotic fluid from early pregnancy reported by others [8,15]. Amniotic fluid is also known to contain other procoagulant factors [12], The discrepancy between our results and oth ers may be explained by the highly sensitive test system used in this study.…”

“…This is not sur prising, since several studies have found a significant variation among different subjects in the thromboplastin synthesis tested in other systems [6,16,17], When two groups of amniotic fluids from early and late pregnancies were compared, the mean thromboplastin activity in both se diment and supernatant was higher in late pregnancy although statistically not signifi cant. In contrast to earlier reports [5,8,15], our results are not conclusive for an increase in thromboplastin activity with progression of pregnancy.…”

“…Weiner et al [14] demonstrated that amniotic fluid was thrombogenic in that it initiated the con version of prothrombin to thrombin. Phillips and Davidson [8] demonstrated that the clotaccelerating activity of amniotic fluid was more similar to that of Russell's viper venom than to that of thromboplastin. According to Phillips and Davidson [8] the procoagulant activity is an activator of factor X and this activation appears to increase with progres sion of gestation.…”

“…Phillips and Davidson [8] demonstrated that the clotaccelerating activity of amniotic fluid was more similar to that of Russell's viper venom than to that of thromboplastin. According to Phillips and Davidson [8] the procoagulant activity is an activator of factor X and this activation appears to increase with progres sion of gestation. Hastwell [4] suggests that acceleration of clotting time of whole blood is due to the thromboplastin activity of am niotic fluid using a method by adding blood to a sample of amniotic fluid.…”

Changes in amniotic fluid concentration of thrombin–antithrombin III complexes in patients with preterm labor: Evidence of an increased thrombin generation

“…These findings, along with the high molecular weight of thrombin (39,000 Daltons), suggest that thrombin is produced locally. Evidence in support of this view includes the following: 1) Prothrombin[91] and other coagulation factors from both the intrinsic and extrinsic pathways are present in amniotic fluid[91,92]; 2) Tissue factor is present in amniotic fluid in high concentrations and can directly convert prothrombin to thrombin[17,65,68,93–95]; and 3) The local production of thrombin is via activated factor X, as it has been demonstrated that amniotic fluid has direct factor X-activating properties[96]. Collectively, these observations provide a mechanism for the local generation of thrombin from prothrombin in the amniotic fluid.…”