Effect of acetone precipitation on the clinical prediction of respiratory distress syndrome when utilizing amniotic fluid lecithin/sphingomyelin ratios.

Amniotic fluid lecithin-to-sphingomyelin ratios are widely used to predict fetal lung maturity. The inclusion of acetone precipitation in the determination of the lecithin/sphingomyelin ratio has been widely accepted as a necessary step for enhancing predictivity. The lecithin/sphingomyelin ratio of 181 amniotic fluid samples was analyzed with and without acetone precipitation. Sensitivity, specificity, and predictive values were compared. Although there was a significant difference in the numeric value (p less than 0.001) between the two methods, the clinical prediction of the respiratory distress syndrome was not significantly enhanced by acetone precipitation. We conclude that acetone precipitation fails to improve the prediction of fetal lung maturity by lecithin/sphingomyelin ratio analysis.