Prenatal diagnosis of tetralogy of fallot by Doppler color flow mapping

The prenatal diagnosis of tetralogy of Fallot (TOF) can be difficult, as the routine sonographic four-chamber view may be normal before birth. Unlike the normal fetus, in which blood flows adjacent to the left side of the interventricular septum, on color Doppler mapping a fetus with TOF also demonstrates antegrade flow along the right side of the interventricular septum. This Y-shaped ventricular outflow passing through the dilated aortic tract is confluent at the level of the ventricular septal defect during the systolic phase. In the past 3 years, three cases of TOF have been diagnosed prenatally at the Chang Gung Memorial Hospital. In each case, the above picture was demonstrated. 2-Dimensional Doppler color flow mapping may be helpful in the prenatal diagnosis of TOF.