Left and right lung volumes in fetuses with diaphragmatic hernia.

OBJECTIVE To compare the volume of the ipsilateral and contralateral lungs in fetuses with congenital diaphragmatic hernia (CDH). METHODS Left and right lung volumes were measured using three-dimensional (3D) ultrasonography in 42 fetuses with CDH at median 26 (range, 20-32) weeks of gestation. Each value was then expressed as a difference, in standard deviations, from the normal mean for gestation, previously established from the study of 650 normal fetuses at 12-32 weeks (Z-score). The Mann-Whitney U-test was used to determine the significance of the differences between the measurements in fetuses with CDH and normal fetuses and between the ipsilateral and contralateral lungs in fetuses with left- and right-sided CDH. RESULTS There were 34 fetuses with left-sided CDH and eight with right-sided CDH. In CDH both the ipsilateral and contralateral lung volumes were substantially lower than in normal fetuses. In left CDH the left lung volume was 4.03 (median; range, 3.11-4.78) SDs below the normal mean for gestation, and the respective values for the right lung were 3.04 (median; range, 1.78-4.31) SDs (P < 0.001 for both). In right CDH, the left lung volume was 2.91 (median; range, 1.62-4.07) SDs below the normal mean for gestation and the respective values for the right lung were 4.35 (median; range, 3.07-4.99) SDs (P < 0.001 for both). In both left and right diaphragmatic hernia the deficit in the volume of the ipsilateral lung was significantly greater than the deficit in the contralateral lung. CONCLUSIONS In fetuses with CDH both the ipsilateral and contralateral lung volumes are substantially lower than in normal fetuses.