[Correlation between disaturated phosphatidylcholine in amniotic fluid and fetal lung maturation]

The concentrations of disaturated phosphatidylcholine (DSPC), the major component of pulmonary surfactant, were quantified on 528 amniotic fluid samples, which did not show the contamination of blood or meconium and were uncomplicated by polyhydramnios or severe congenital anomalies incompatible with life. 396 samples of amniotic fluid (29 RDS cases) obtained 72 hours before delivery were used to evaluate the reliability of DSPC as a specific indicator in pedicting fetal lung maturation. DSPCs were determined according to the method described by Mason et al. and lecithin/sphingomyelin (L/S) ratios were measured by using two dimensional thin-layer chromatography. The critical points of DSPC and L/S ratio were defined as 1.0mg/dl, 2.0 respectively. The results are as follows. There was a gradual increase in DSPC levels of amniotic fluid with increasing maturity until 35 weeks of gestational age and a rapid rise from 36 weeks to term. About 70% of the amniotic fluids having a significantly higher DSPC level greater than or equal to 5.0mg/dl within 35 weeks of gestation were found to be obtained from pregnant women whose pregnancy was complicated by PROM, threatened premature labor or cervical incompetency and who eventually underwent preterm labor. Out of 58 samples, in which DSPC and the L/S ratio were measured simultaneously, two markers agreed in 47 cases in an immature or a mature value for predicting fetal lung maturation. RDS was correctly predicted in 27 of 60 cases (false negative, 55.0%) with DSPC levels less than 1.0mg/dl. When DSPC levels were 1.0mg/dl or more, there were only two of 336 (0.6%), false positives.(ABSTRACT TRUNCATED AT 250 WORDS)