A new method of evaluating fetal lung maturity: the enzymatic lecithin determination in amniotic fluid.
The concentration of phospholipids is well suited as indicator for the prognosis of a possibly postnatal respiratory distress syndrome. The method used most frequently up to now has been the determination of the lecithin/sphingomyelin ratio (L/S ratio) by thin layer chromatography. We have developed a specific assay for the quantitative determination of lecithin in amniotic fluid, which yields absolute concentration values and does not require the determination of a concentration ratio. Lecithin is hydrolized by phospholipase C and alkaline phosphatase. Choline is determined afterwards by a highly specific choline kinase from yeast. The total time required is less than 2 h. The usual lecithin concentration present in the 35th to 38th wk of gestation can be determined with a coefficient of variation of 2-3% (n=30). Fetal lung maturity can be expected at a lecithin concentration above 4.7-5.1 mg/100 ml. The method compares well with the L/S ratio. Detailed data about clinical significance will be presented. Good precision accuracy and simple handling make enzymatic lecithin determinations suitable for routine use.
D000653:Amniotic Fluid / Q000201:enzymology*; D005260:Female; D005325:Fetal Organ Maturity; D006801:Humans; D007231:Infant, Newborn; D008168:Lung / Q000196:embryology*; D008722:Methods; D010713:Phosphatidylcholines / Q000032:analysis*; D011247:Pregnancy; D011296:Prenatal Diagnosis; D012127:Respiratory Distress Syndrome, Newborn / Q000175:diagnosis; D013109:Sphingomyelins / Q000032:analysis
D010713:Phosphatidylcholines; D013109:Sphingomyelins