Rapid enzyme analysis of amniotic fluid phospholipids containing choline: a comparison with the lecithin to sphingomyelin ratio in prenatal assessment of fetal lung maturity.

The relation between the choline containing surfactant phospholipids lecithin and sphingomyelin in amniotic fluid and fetal lung maturity is well established. An enzymatic method that had been automated and optimised for use on a centrifugal analyser was used to measure the total choline containing phospholipids in amniotic fluid. The total time taken for this assay was 10 minutes. The results obtained from 100 patient samples, using this procedure, compared favourably with the results obtained by the thin layer chromatography procedure used to determine the lecithin to sphingomyelin ratio (r = 0.93). A clinical study of 60 patients showed that this assay predicted prenatal respiratory distress syndrome as well as the lecithin to sphingomyelin ratios. The advantage of this assay over existing procedures is that it requires minimum preparation of the specimen and no extraction, is quick, and shows a high degree of precision.