Increasingly, paediatric cardiologists are called upon to diagnose cardiac malformations prenatally. In the main, the types of malformation seen during fetal life will be similar to those documented postnatally, but the frequency with which they are encountered, as well as the views that can be used for diagnosis, will be different. This review aims to describe the anatomic spectrum of malformations seen in 917 fetal hearts examined consecutively following prenatal diagnosis. The distribution of anomalies is illustrated in terms of a simple sweep through the fetal thorax passing from the four-chamber plane to the outflow tracts, and then to more cranial views of the mediastinum. Two-thirds of the anomalies described would have been detectable in the four-chamber plane. Some, such as tricuspid valvar abnormalities, will alter the normal appearances of the four-chambers dramatically. In terms of the overall spectrum, however, such obvious abnormalities only form a minor part of the total number. Others, such as atrioventricular septal defect, will often require closer inspection of intracardiac anatomy, but will make up a large proportion of the entire cohort. Up to one third of the anomalies in the series would have required views more cranial to the four-chamber plane of section. In these, it would have been necessary to examine the nature of the left ventricular outflow tract, the crossing of the two outflows, or else the arterial arches in order to secure detection. In the fetus, these and other planes must be considered by the echocardiographer in order completely to detect and document the entire spectrum of cardiac abnormalities likely to be encountered.
