[Comparison of five different ultrasonographic parameters for diagnosis of lethal fetal pulmonary hypoplasia]

To evaluate the clinic value of five different ultrasonographic fetal parameters for prenatal diagnosis of pulmonary hypoplasia.

Two hundred and seventy-one normal singleton pregnancies with well-established dates between 20 and 40 weeks of gestation were studied to establish normal reference range of five different ultrasonographic fetal parameters. The five parameters, which could reflect fetal lung mass, were as follows: lung area/body weight ratio, lung area, thoracic circumference/ abdominal circumference ratio, lung area/thoracic area ratio and lung area/head circumference. Thirty pregnancies with risk factors for pulmonary hyperplasia were studied for the usefulness of five parameters. Two or more standard deviations below the mean control group measurement were considered abnormal. The prenatal ultrasonic diagnoses of pulmonary hyperplasia were confirmed at neonatal follow-up examinations, on autopsy and by pathologic findings.

Lung area and lung area/head circumference increased with gestational age, lung area /body weight ratio decreased with gestational age. The relationships among the two ratios (thoracic circumference/abdominal circumference ratio, lung area/thoracic area ratio) and gestational age were relatively constant. Abnormal lung area/body weight ratio had a higher diagnostic accuracy than other parameters. Sensitivity of the parameters, including lung area, lung area/body weight ratio, thoracic circumference/abdominal circumference ratio, lung area/thoracic area ratio and lung area/head circumference were 83%, 97%, 50%, 70% and 87% , respectively. Sensitivity of the lung area/body weight ratio was 95% (20/21 fetuses); specificity, 9/9 fetuses; positive predictive value, 100% (20/20 fetuses); negative predictive value, 9/10; and accuracy 97% (29/30 fetuses).

Lung area/ body weight ratio is a good predictor of pulmonary hypoplasia.