Isolated left-sided congenital diaphragmatic hernia: cardiac axis and displacement before fetal viability has no role in predicting postnatal outcome

The purpose of this retrospective study was to determine whether objective assessment of cardiac shifting on two-dimensional ultrasonography can predict postnatal outcome in fetuses with isolated left-sided congenital diaphragmatic hernia (CDH).

Still images at the level of the four-chamber view were obtained in 23 fetuses with left-sided CDH. A group of 12 fetuses (3 non-survivors and 9 survivors) were examined at two periods, between 20 and 30 weeks and between 31 and 40 weeks. A further 11 fetuses (2 non-survivors and 9 survivors) were examined between 31 and 40 weeks. Fetal heart axis and position were determined manually and associated with postnatal outcome.

The cardiac axis remained constant in the 9 survivors (15.5 +/- 3.2 versus 17.2 +/- 3.3, p = 0.71) and 3 non-survivors (19.0 +/- 11.5 versus 18.5 +/- 11.8, p = 0.97). There was no statistical difference between the 9 survivors and 3 non-survivors at the two periods. Cardiac displacement remained constant in the 9 survivors (0.2 +/- 0.02 versus 0.2 +/- 0.02, p = 0.32) but increased significantly in the 3 non-survivors (0.2 +/- 0.04 versus 0.4 +/- 0.02, p = 0.015). The difference between survivors and non-survivors was statistically significant between the18 survivors and 5 non-survivors examined between 31 and 40 weeks of gestation (0.2 +/- 0.02 versus 0.4 +/- 0.02, p = 0.037).

This study does not support the hypothesis that objective assessment of mediastinal shift in fetuses with left-sided CDH has a role in predicting postnatal outcome before fetal viability, which is when it would be more useful for counseling patients regarding whether to continue with the pregnancy or to opt for termination.