Sonographic predictors of survival in fetal diaphragmatic hernia

The authors studied the predictive value of detailed fetal sonographic parameters on outcome for 55 patients with prenatally diagnosed congenital diaphragmatic hernia managed at an ECMO center. Their sonographic assessment included gestational age at time of diagnosis, polyhydramnios (largest amniotic fluid pocket diameter), presence of liver and/or stomach herniation, and abdominal circumference at the level of the umbilical cord. They measured the right lung two-dimensional area at the level of the atria as an estimate of lung size and mediastinal shift. The ratio of right lung area to head circumference (LHR) was calculated to minimize lung size differences owing to gestational age. The principal outcome variable was survival. The overall survival rate was 65%. If the diagnosis was made after 25 weeks' gestation, the survival rate was 100% (12 of 12); the rate was 56% if the diagnosis was made at or before 25 weeks (P < .005). All five neonates with an LHR of less than 0.6 died; the survival rate was 100% for those whose LHR was greater than 1.35; and those with an LHR between 0.6 and 1.35 had a 61% survival rate (P < .001). The survival rate for those whose liver was not herniated was 100% (10 of 10); herniation of the liver decreased the survival rate to 56% (P < .05). Stomach position, polyhydramos, and abdominal circumference were not found to be useful survival predictors. No prenatal sonographic parameter was absolutely predictive of postnatal death except very small right lung size, which was present in only 5 of the 55 patients. Survival is highly likely if the liver is not herniated into the thorax and/or the right lung is large.