The lung-to-thorax transverse area ratio at term and near term correlates with survival in isolated congenital diaphragmatic hernia.

OBJECTIVE: The purpose of this study was to determine how well liver position, the lung area-to-head circumference (L/H) ratio, and the lung-to-thorax transverse area (L/T) ratio predicted the need for extra-corporeal membrane oxygenation (ECMO) and survival in fetuses with isolated congenital diaphragmatic hernia (CDH).

METHODS: Antenatal records of 25 fetuses with isolated left-sided CDH who were born by cesarean delivery under fetal stabilization at this institution were reviewed. The latest determinations of the L/H and L/T ratios before birth (between 34 and 38 weeks' gestation) were compared on the basis of the cutoff points for mortality: less than 1.0 versus 1.0 or greater for the L/H ratio and 0.08 or less versus greater than 0.08 for the L/T ratio. Outcome measures assessed were survival (discharge to home) and the need for ECMO.

RESULTS: Overall survival was 64% (16/25). Postnatal survival in fetuses with an L/T ratio of 0.08 or less was statistically lower than in those with an L/T ratio of greater than 0.08 (33% versus 81%; P = .0308). The percentage requiring ECMO in the group with an L/T ratio of 0.08 or less was also higher than that of the group with an L/T ratio of greater than 0.08, but the difference was not statistically significant (67% versus 25%; P = .0872). Neither the L/H ratio nor herniation of the fetal liver into the chest affected survival or the need for ECMO.

CONCLUSIONS: In fetuses with isolated CDH at term or near term, the L/T ratio may be a better predictor of outcome than the L/H ratio or liver herniation.