title: A modified lecithin/sphingomyelin ratio test for fetal maturity.
abstract: Several desirable techniques (rapid chromatogram development, planimetry, acetone precipitation of lecithin, and copper molybdate staining) used in other published lecithin/sphingomyelin (L/S) ratio procedures were integrated into a single L/S ratio test. The resulting test requires only 2 ml of amniotic fluid, can be performed within 75 minutes, and is semiquantitative. Methodology tests showed a high degree of reproducibility without the need for a densitometer: Coefficients of variation for the standards and amniotic fluid samples were 11% and 4%, respectively. Also, a linear relationship was observed between the L/S weight ratios in synthetic mixtures and the corresponding area ratios up to the mature value of 2.5. Clinical evaluation on a normal and high-risk patient population showed excellent reliability: The accuracy in predicting fetal lung maturity and immaturity was 100% and 85%, respectively. Moreover, the numerical value of the L/S ratio in the immature range was found to be indicative of the severity of respiratory distress syndrome. Finally, the relationship between the L/S ratio and gestational age in a normal population was described mathematically by an approximating curve. We concluded from our methodologic and clinical data that the L/S ratio may be determined simply and reliably by means of the procedure described in this report.
mesh_terms: D000653:Amniotic Fluid / Q000032:analysis*; D002855:Chromatography, Thin Layer; D005260:Female; D005333:Fetus / Q000502:physiology; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D008168:Lung / Q000196:embryology*; D008722:Methods; D010713:Phosphatidylcholines / Q000032:analysis*; D011247:Pregnancy; D011296:Prenatal Diagnosis / Q000379:methods*; D012127:Respiratory Distress Syndrome, Newborn / Q000175:diagnosis; D013109:Sphingomyelins / Q000032:analysis*
chemical_list: D010713:Phosphatidylcholines; D013109:Sphingomyelins