Abstract
Both tissue thromboplastin and pulmonary surfactant show electron-microscopically lamellar structure and belong chemically to lipoprotein. Based on the assumption that the thromboplastic activity of the amniotic fluid is mainly due to pulmonary surfactant in the amniotic fluid, this study was done and the following results were obtained: (1) Pulmonary surfactant isolated from the amniotic fluid shortened the activity of plasma recalcification time (PRCT) with dose response. (2) The thromboplastic activity of the amniotic fluid increased with advancing gestational ages. (3) Shortening ratio of PRCT calculated from the following formula, (control PRCT-test PRCT)/control PRCT, was more than 32% when surfactant phospholipid was more than 1mg/dl of amniotic fluid which indicates sufficient maturation of the fetal lung. (4) There was a close correlationship between shake test, a simple rapid screening test for assesment of fetal lung maturity, and shortening ratio of PRCT. (5) From the neutralization effect of heparin on thromboplastic activity of amniotic fluid, 5 units of heparin were calculated to be sufficient to neutralize the thromboplastic activity of 1ml of amniotic fluid. This calculation will be of help in heparin therapy of amniotic fluid embolism.
