Fetal echocardiography. VIII. Aortic root dilatation--a marker for tetralogy of Fallot.

Tetralogy of Fallot has increased in incidence during the past decade. Although abnormalities of the four-chamber screening examination of the fetal heart identifies structural anomalies associated with semilunar and atrioventricular valve hypoplasias, the anomalies associated with tetralogy of Fallot are not as readily identifiable from the four-chamber view alone. This study was designed to determine whether aortic root dilatation, commonly observed in the newborn with tetralogy of Fallot, is a marker for tetralogy of Fallot diagnosed in utero. In 45 normal (control) fetuses the biparietal diameter, head circumference, abdominal circumference, and femur length were measured and M-mode measurements were made of the biventricular outer dimension and aortic root dimension. The aortic root dimension from seven fetuses (18, 19, 20, 23, 32, 33, and 34 weeks' gestation) with tetralogy of Fallot was increased in dimension when compared with cardiac (biventricular outer dimension) and noncardiac biparietal diameter, head and abdomen circumferences, and femur length parameters. In conclusion, incorporation of aortic root imaging with the four-chamber view of the fetal heart during a routine screening examination allows for identification of fetuses with tetralogy of Fallot.