Fetal lung to liver reflectivity ratio and lung maturity

A pilot study examined 23 patients who underwent simultaneous ultrasound and amniocentesis to determine whether the ratio of densitometrically determined tissue densities of fetal lung and liver correlate with the L/S, the OD 650, or phosphatidylglycerol levels. The incidence of a lung/liver ratio greater than 1 of 65% was similar to that of maturity levels of the standard tests. However, there was no statistically significant correlation between an L/L greater than 1 and/or any maturity parameter tested, nor was there any correlation with the absence of pulmonary maturity. We conclude that this test cannot be reliably used to predict L/S, OD 650 reading, or PG levels.