Correlation of amylase and lecithin sphingomyelin ratios in amniotic fluid samples.
The use of amniotic fluid amylase (AF amylase) has been proposed as a screening test to determine fetal maturity. We reviewed data from 944 amniotic fluid samples analyzed by our laboratory for amylase and lecithin sphingomyelin (L/S) ratio between 1975 and 1980. AF amylase shows poor overall correlation with L/S ratios (r = 0.256). Retrospective analysis of AF amylase as a screen to determine the need for L/S ratios showed an overall sensitivity of 57%, and an overall specificity of 86% for AF amylase. Three groups were studied: a low amylase group (amylase less than 200 U/L), a middle group (amylase 200-300 U/L), and a high amylase group (amylase greater than 300 U/L). Only 55% of the low amylase group had an immature L/S ratio. The high amylase group had the best correlation between AF amylase and L/S ratio, but 13% of these samples had an immature or borderline L/S ratio. We conclude that AF amylase cannot be used as a screening test to determine the need to perform L/S ratios.
D000653:Amniotic Fluid / Q000032:analysis* / Q000201:enzymology; D000681:Amylases / Q000032:analysis*; D005189:False Positive Reactions; D005325:Fetal Organ Maturity; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D008168:Lung / Q000196:embryology; D010713:Phosphatidylcholines / Q000032:analysis*; D012127:Respiratory Distress Syndrome, Newborn / Q000175:diagnosis; D013109:Sphingomyelins / Q000032:analysis*
D010713:Phosphatidylcholines; D013109:Sphingomyelins; D000681:Amylases