New neonatal problems of blood coagulation and fibrinolysis. II. Thromboplastic effect of amniotic fluid and its relation to lung maturity.

Pulmonary hyaline membrane disease in newborn infants is considered an abnormality in the alveolar lining layer. Quantitative analysis of this surfactant is necessary for the intrauterine diagnosis of lung maturity of the fetus. The presence of surfactant in amniotic fluid has been demonstrated by the shaking method [1]. But it is also well known that amniotic fluid has a thromboplastic effect [3,6]. In order to compare the correlation between the shaking method and the thromboplastic effect of the amniotic fluid, recalcification time and partial thromboplastin time were measured with and without amniotic fluid using an aggregation-meter. In each of 15 cases, a shortening of these times was recorded after the addition of amniotic fluid after the 30th week of pregnancy. In all cases the addition of amniotic fluid resulting in shortening these times. Surfactant seems to have enhancing effect on the coagulation. These results demonstrate the presence of surfactant in amniotic fluid in agreement with the results of the shaking method. Although these methods are of limited utility as quantitative assays for surfactant, they are of sufficient accuracy and of great value for clinical diagnosis.