Evaluation and evolution during time of prenatal diagnosis of congenital heart diseases by routine fetal ultrasonographic examination.

The objectives of this study were to evaluate routine prenatal diagnosis of congenital heart diseases (CHD) by fetal ultrasound examination in a well-defined population during the period 1994-1999 and to compare these results with the results from 1979 to 1993. This study included 80,076 consecutive pregnancies of known outcome from 1994 to 1999. CHD were classified as isolated or associated when at least one other major extra-cardiac malformation was present. Only 137 out of 688 malformed fetuses with CHD without chromosomal anomalies were detected (19.9%). The sensitivity of detection varied from 61.9% for malformations such as isolated hypoplastic left heart and single ventricle, to around 7-19% for atrial and ventricular septal defects. Prenatal detection rate of CHD was 11.4% for isolated cases, and 40.2% for multiple malformed with CHD. The gestational age at discovery varied from 16 to 36 weeks. There is no upper limit for termination of pregnancies in our country; 12.3% of all pregnancies were terminated after prenatal diagnosis. However, 62% of the pregnancies with a CHD detected prenatally were terminated. The detection rate of CHD increased during time from 9.2% during the period 1979-1988 to 13.7% during the period 1990-1993 and to 19.1% during the period 1994-1999. Our study shows large variation in the prenatal detection rate of CHD. Prenatal diagnosis of CHD is significantly higher when associated malformations are present. Cardiac defects affecting the size of the ventricles have the highest detection rate. Gestational age at discovery was 20-24 weeks for the majority of associated cardiac defects. The prenatal detection rate of CHD increased during time from 1979 to 1999.