Determination of amniotic fluid phospholipids for the diagnosis of fetal maturation

In 111 patients, the L/S ratio, the concentration of phospholipids, lecithin, phosphate in total lipids, creatinine, and the foam test were determined at various periods of gestation by amniocentesis. Surface tension of amniotic fluid was measured by two different techniques (the angle of intersection and the bubble disappearance rate). Each test, with the exception of the angle of intersection and the concentration of phosphate in total lipids, correlates significantly with gestational age and with the L/S ratio of Gluck and Kulovich. The S.D. of each test is large. From the data it is concluded that the determination of amniotic fluid creatinine concentration and the use of the foam test provide fast, cheap, and reliable information when the tests are positive for maturation. If the amniotic fluid tests are in the immature range, amniocentesis should be repeated.