Objective To assess the value of antenatally determined observed to expected fetal lung area to head circumference ratio (LHR) in the prediction of postnatal survival in isolated, congenital diaphragmatic hernia (CDH). Methods Results In both the normal fetuses and those with CDH the LHR increased but the observed to expected LHR did not change significantly with gestational age. In normal fetuses the mean observed to expected LHR in the left lung was 100% (95% CI, 61-139%) and in the right lung it was 100% (95% CI, 67-133%). In fetuses with CDH the mean observed to expected LHR was 39% (range 7-79%). Regression analysis demonstrated that significant predictors of survival were the observed to expected LHR (odds ratio (OR) 1.09, 95% CI, side of CDH (left side OR 11.14, 95% CI, and gestational age at delivery (OR 1.18, 95% CI,). ConclusionIn CDH, the LHR increases while observed to expected LHR is independent of gestational age. In fetuses with both left-and right-sided CDH, measurement of the observed to expected LHR provides a useful prediction of subsequent survival.

Objective To establish reference intervals with gestation for the right and left lung areas and lung area to head circumference ratio (LHR). Methods

In normal fetuses the lung and heart volumes increase between 12 and 32 weeks of gestation. The extent to which in pathological pregnancies possible deviations in these measurements from normal prove to be useful in the prediction of outcome remains to be determined.