Fetal echocardiography. VI. Assessment of cardiothoracic disproportion--a new technique for the diagnosis of thoracic hypoplasia.

Fifty-eight fetuses were studied with use of diagnostic real-time and M-mode ultrasound between 15 and 40 weeks of gestation in which the chest circumference, biventricular outer dimension of the heart, biparietal diameter, head circumference, abdominal circumference, and femur length were measured. The chest circumference correlated with the biparietal diameter (r = 0.978), head circumference (r = 0.977), abdominal circumference (r = 0.989), femur length (r = 0.983), and biventricular outer dimension (r = 0.972). Regression analysis with predicted mean and 95% and 5% confidence limits demonstrated a linear relationship between the chest circumference and the following: biparietal diameter, head circumference, abdominal circumference, femur length, and biventricular outer dimension. Four representative cases (triploidy [69,XXX], osteogenesis imperfecta, intrauterine growth retardation, and renal agenesis) illustrate the usefulness of the data when thoracic hypoplasia is suspected.