Fibrinolytic components in fetal membranes and amniotic fluid.

Abstract

We evaluated fibrinolytic components in plasma and amniotic fluid of pregnant women and in postpartum fetal membranes. Fibrinolytic parameters in amniotic fluid and plasma were measured by means of enzyme-linked immunosorbent assays. Fetal membranes collected after spontaneous labor at term were analyzed by immunohistochemical methods with immunospecific antibodies against fibrinolytic components. Amniotic fluid contained high plasminogen activator inhibitor-1 concentrations but had low activity. Strong staining for plasminogen activator inhibitor-1 and vitronectin was observed in chorionic trophoblasts and moderate staining in decidual connective tissue. Strong staining for plasminogen activator inhibitor-2 was seen in decidual cells. Although prominent staining of plasminogen activators and plasminogen were observed in the amniotic epithelium, virtually no plasminogen activator inhibitor-1, plasminogen activator inhibitor-2, or alpha 2-plasmin inhibitor staining was detected. The delicate balance of fibrinolytic activators and inhibitors in fetal membranes and amniotic fluid may contribute to the triggering of membrane rupture at term.