In 180, several reports appeared almost simultaneously of the identification of normal cardiac anatomy in fetal life. The recognition of several different forms of structural cardiac anomaly followed soon after. At this time, cardiac evaluation was confined to pregnancies at increased risk of congenital heart disease (CHD), such as those with a family history of CHD or where extracardiac malformations had been detected. However, up to 90% of CHD occurs in pregnancies where there are no known high risk features. For this reason, in 1985 a group based in Paris put forward the idea of teaching the obstetrician to assess the heart in a simplified form during routine obstetric scanning, which was well established at that time in France. As a result, four chamber view scanning became an integral part of the fetal anatomical survey in many countries by the end of the 1980s. In the early 1990s, some authors suggested extending the cardiac assessment to include great artery scanning in order to detect a higher proportion of cases of major congenital heart disease.1 If cardiac screening is confined to the four chamber view, about 2/1000 studies will be abnormal and would represent about 60% of the major heart disease seen in infants. If the great arteries are also examined, about 3/1000 cases would be abnormal, and over 90% of major heart disease would be detectable prenatally. Therefore, in ideal circumstances, the vast majority of serious heart malformations could be detected before 20 weeks' gestation. Unfortunately, the reality is far from this for several reasons:

• differing policies for obstetric scanning

• differing guidelines for scanning

• differing skill at scanning.

About 2% of live births have fetal structural malformations, the majority of which can be detected by ultrasound. About 25% of these malformations are cardiac in nature and about half of …