Amniostat FLM: a new technique for detection of phosphatidylglycerol in amniotic fluid

Amniostat-FLM (AFLM) is an immunologic semi-quantitative slide agglutination test for determining the presence of phosphatidylglycerol (PG) in amniotic fluid. We analyzed 178 samples for the presence of PG by both AFLM and our standard thin-layer chromatographic technique (TLC). Both tests agreed in 135 of 178 cases. All fluids with a mature AFLM had PG detected by TLC assay. All of the 43 discordant samples were classified as immature by AFLM although PG was present by TLC. Among the 151 patients who delivered within 72 hours of amniocentesis, 17 cases of respiratory distress syndrome (RDS) occurred. All were correctly predicted by immature tests. However, an immature AFLM was associated with RDS in only 21% of cases (11/53) while 37% of cases (17/46) with an immature TLC test resulted in neonates with RDS. We conclude that the AFLM is a very simple, rapid, and sensitive test for identifying infants who will develop RDS but is less specific than the TLC assay. Though a mature AFLM will predict fetal pulmonary maturity, an immature result should be confirmed by thin-layer chromatographic analysis.