ABSTRACT
Introduction Congenital heart disease (CHD) is the most common major congenital malformation, affecting approximately 6:1,000 live births.1 The epidemiology of CHD is discussed in Chapter 6. The majority of cases of CHD do not cluster in families or populations, but rather occur in low-risk patients. In addition, a fetus diagnosed with CHD is at increased risk of chromosomal abnormalities.2-6 Cardiac malformations are common in spontaneously aborted fetuses.7 Major chromosomal abnormalities are found in spontaneously aborted fetuses (57%),6 midtrimester fetuses (18%), and live births affected by significant CHD (12%).2,3 When extracardiac malformations are present, this rate can be as high as 66%.5 The overall risk of aneuploidy in a fetus with CHD is estimated to be 30%.2-4,6 Therefore, the prenatal diagnosis of CHD is an indication for fetal genetic investigation. While CHD is one of the most clinically significant malformations amenable to prenatal ultrasonographic diagnosis, it is also the most commonly missed during fetal scans.
