The reliability and clinical use of a rapid phosphatidylglycerol assay in normal and diabetic pregnancies

Lecithin phosphorus concentration, the standard fetal lung maturity test in our institution, and phosphatidylglyercol were assayed in 69, 29, and 45 amniotic fluid samples from normal (GI), gestational (GII), and insulin-dependent diabetic (GIII) women by means of thin layer chromatography and Amniostat-FLM, respectively. Lecithin phosphorus concentration ≥0.1 mg/dl and positive or strong positive Amniostat-FLM results were considered mature. The results of both assays were concordant in 79% of the samples. The discordance rate was highest in Gill patients. In our experience, respiratory distress syndrome did not develop in neonate infants of diabetic women delivered after a mature lecithin result. With lecithin phosphorus concentration as the reference standard, the predictive value of a mature Amniostat-FLM result was 96.2%, whereas that of an immature result was 58.5%. Respiratory distress syndrome occurred in only two Gill neonates who were delivered within 72 hours of both immature lecithin and Amniostat-FLM results. These findings support the use of Amniostat-FLM as a screening test for fetal lung maturity in both normal and diabetic pregnancies. Additional tests will be necessary to evaluate further fetal lung maturity only if the results are negative.