Comparison of the values for filter-trapped phospholipids with those for the lecithin/sphingomyelin ratio of amniotic fluid. A preliminary report.

A comparison was made between the lecithin/sphingomyelin ratio of amniotic fluid and the amount of phospholipids which could be removed from the amniotic fluid by filtration. We found a good correlation between the two methods. The amount of filter-trapped phospholipids can be determined within one and a half hours compared to three and a half hours for the lecithin/sphingomyelin ratio. It has a higher reproducibility than the lecithin/sphingomyelin ratio and can be performed with the aid of a simple filtration apparatus.