COMPARATIVE-ANALYSIS OF THE L S METHOD AN D THE TDX-FLM ASSAY FOR ASSESSING FETAL LUNG MATURITY IN-UTERO/

Two methods employed in fetal lung maturity assessment, the TDx-Fetal lung maturity (FLM)-assay that measures the relative concentrations of surfactant and albumin in the amniotic fluid, and the lecithin/sphing omyelin ratio were compared in predicting the likelihood of neonatal r espiratory distress syndrome (RDS). Neither the TDx-FLM assay nor the L/s-ratio differentiate per-fectly between RDS and non-RDS cases. Comp aring the ROC analyses of these two diagnostic and prognostic systems the TDx-FLM assay appears to have a better capacity to discriminate. D ue to its weak performance in respect of differentiation, the L/S-rati o should be used clinically with caution. The use of one single cut-of f point might not be appropriate; the chosen cut-off point should be a dapted to the clinical situation, i. e. to maternal and fetal risk fac tors. In a low-risk situation the L/S cut-off point should be 2.6 and the the TDx-FLM cut-off point 28. In a high-risk situation the cut-off point should be selected according to the clinical situation. Due to the lack of discriminating capacity the traditionally used and most wi dley accepted LIS cut-off point 2 should be used only with extreme cau tion. The correlation between L/S and TDx-FLM values is weak at the be ginning of the third trimenon (approximately 28 to week 32 weeks of ge station), but is improving as pregnancy progresses until term. While a t the beginning of the third trimenon the L/S values start to rise sig nificantly with time, the obtained TDx FLM values change very little. During this period of time, the use of the L/S-ratio might be favourab le, compared to the use of the TDx-FLM assay. The combination of both methods, starting at 32/33 weeks of gestation, however, might improve the monitoring and prediction of fetal lung development.