Assessment of a rapid test on amniotic fluid for estimating fetal lung maturity

We have measured the absorbance of centrifuged amniotic fluids at 650 nm. and found reasonably good correlation between the absorbance and the L/S ratio. In 87 fluids studied, an absorbance of greater than 0.100 predicted correctly an L/S ratio of 2 or more in 98 per cent of the cases. When the absorbance was less than 0.100, 70 per cent of the fluids had an L/S ratio of less than 2.