The role of coagulation and fibrinolysis in preeclampsia.

The coagulation and fibrinolytic systems play a key role in maintaining the integrity and patency of the vascular compartment. Pregnancy induces extensive physiological changes in these systems, thus creating an enhanced capacity to produce fibrin and a diminished ability to remove it. Fibrin deposition localized to the uteroplacental circulation is a feature of normal pregnancy. In women with fatal eclampsia, disseminated intravascular coagulation with fibrin deposition in the renal glomeruli is well documented. The condition of preeclampsia is not well defined. Nonetheless, evidence of intravascular coagulation, as shown by elevated levels of fibrin degradation products and reduced platelet counts, has been found in many women with preeclampsia. Serial studies showed that thrombin generation, as indicated by the ratio of factor VIII-related antigen to factor VIII coagulant activity, is considerably in excess of that which occurs in normal pregnancy, and its appearance coincides with the development of the clinical features of preeclampsia. Heparin therapy has bot been proven of value in established preeclampsia, but this fact does not disprove that role that intravascular coagulation may play in the pathogenesis of the disease. A controlled trial ina high-risk group of low-dose he;arin and an antiplatelet agent from the 16th to the 18th weeks of pregnancy onwards is required to elucidate the role of intravascular coagulation in preeclapmsia and its effect on the fetus.