[Biomechanic examination of prenatal lung maturity. Testing of amniotic fluid specimens and lung homogenates on Wilhelmy's scale].

In all traditional methods of determining fetal lung maturity the content of phospholipids in the amniotic fluid is used as parameter. The function of the other parts of the surfactant is not taken into account. The dynamic surface tension measurements using the Wilhelmy balance simulate the interplay of the whole biological system. We have tested 76 specimens of amniotic fluid and 17 lung extracts from 25 weeks' gestation onwards using the biomechanical procedure. In addition, the L/S ratio in the amniotic fluid was determined. There was a correspondence between the values of the amniotic fluid and the lung measured in the same week of pregnancy. The results of the surface tension measurements show a good correlation with the standard method. The following are the advantages of the Wilhelmy balance: results show a small range of dispersion, procedure can be easily learned and carried out quickly and simply.