Amniotic fluid phospholipids and fetal lung maturity. I. Assessment of various methods of determining lecithin and sphingomyelin.
The measurement of the lecithin/sphingomyelin ratio in amniotic fluid as an index of fetal lung maturity has been a controversial and much-discussed topic since the initial report of this procedure appeared in the literature in 1971. Our laboratory has investigated several methods of measuring phospholipid components of amniotic fluid and compared relative reproducibility and accuracy. Correlation of these phospholipid determinations with the clinical presence or absence and relative severity of neonatal respiratory distress syndrome forms the basis of this report. Our findings indicate that careful attention to the biochemical basis of this test results in the ability to predict with great accuracy developmental respiratory distress syndrome. This presentation describes our method of determining lecithin/sphingomyelin ratios in amniotic fluid, compares our results with other tests for determining fetal maturity, and assesses the value of this procedure in clinical situations.