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Table 1 Antenatal ultrasound predictors of survival in CDH

From: Congenital Diaphragmatic hernia – a review

A. LHR is calculated by dividing fetal lung area (mm2) by fetal head circumference (mm). Fetal lung area is usually measured at the level of the four-chamber view of the heart by multiplying the longest diameter of the contralateral lung by its longest perpendicular diameter. Alternatively, some obstetricians trace the lung margin and measure the lung area. The fetal head circumference is measured by its longest electronic ellipse.
a. LHR > 1.35 associated with 100% survival
b. LHR 1.35 to 0.6 associated with 61% survival
c. LHR < 0.6 – no survival
B. Observed to expected LHR (O/E LHR) is calculated by dividing the observed LHR by the expected ratio for gestational age
a. The fetal lung area increases 16-fold compared to 4-fold increase in the head circumference between 12 and 32 weeks’ gestation
b. O/E LHR < 25% is considered severe CDH (survival 10% with liver up and 25% with liver down)
c. O/E LHR < 15% with liver up – 100% mortality
C. Position of liver (or presence of liver herniation)
a. Liver herniation with LHR < 1.0 – 60% mortality
b. Liver in the thorax – 56% survival;