Quantitative determination of phosphatidylglycerol in amniotic fluid by enzymatic assay.

Phosphatidylglycerol (PG) was extracted from 54 human amniotic fluids for the assessment of fetal lung maturity. The PG values were derived from an enzymatic assay involving initial conversion of PG to glycerol by phospholipase C and alkaline phosphatase with subsequent analysis of the glycerol formed. This method proved to be reliable when compared with a method for two-dimensional thin layer chromatographic (2D TLC) analysis of amniotic fluid phospholipids. The results revealed that in all but one of 27 amniotic fluids in which no PG was detected by 2D TLC, enzymatic PG concentrations were less than or equal to 1.5 mumol/l and out of these, from 10 newborn infants delivered within 72 h of sampling, 4 developed respiratory distress syndrome (RDS). Conversely, in all but one of 27 amniotic fluids found to contain PG by 2D TLC, enzymatic PG concentrations were greater than 1.5 mumol/l and except for one subject from non-identical twins, no infants developed RDS.