Evaluation of prenatal diagnosis of congenital heart disease.

Prenatal diagnosis performed by fetal ultrasound scan is now a routine part of antenatal care in many countries. That an increasing number of fetal anomalies may be detected on prenatal ultrasound is beyond doubt. What is possible is not, however, always practical, especially where congenital heart diseases (CHDs) are concerned and when whole antenatal populations are screened rather than high risk groups. Thanks to our registries of congenital anomalies, a retrospective study was undertaken to evaluate the prenatal detection of CHDs by ultrasound scan in 92,021 consecutive pregnancies of known outcome from 1990 to 1993. Only 107 out of 779 malformed fetuses with CHDs without chromosomal anomalies were detected (13.7 per cent). The sensitivity of detection varied from 50 per cent for malformations, such as hypoplastic left heart and single ventricle, to around 5 per cent for ventricular and atrial septal defects. The effectiveness of the detection of some forms of major congenital heart disease has increased since 1987 by including routine examination of the four-chamber view and of the inflow and outflow tracts of the fetal heart. Our results stress the need to obtain a definite, clear, four-chamber view, to perform scans at > 18 weeks' gestation and to train sonographers in order to improve prenatal detection of CHDs.