The sonographic approach to the detection of fetal cardiac anomalies in early pregnancy

Background: Transvaginal sonography enables imaging of the fetal heart in various planes and directions in early pregnancy. This study summarizes our experience in early detection of fetal cardiac anomalies. Methods: Transvaginal sonographic examination was performed in 36 323 consecutive fetuses in both high- and low-risk pregnancies. More than 99% of cases were evaluated at 14-16 weeks' gestation. Examination of the cardiovascular system did not rely on still images of the classic views but instead was performed in a dynamic mode visualizing the heart and great vessels from different directions and in various scanning planes. Results: Cardiac anomalies were detected in 173 fetuses, giving an overall incidence of 1 in 210 pregnancies. In 44% of these, the cardiac anomaly was isolated. An abnormal karyotype was detected in 27 of the 72 cases that underwent chromosomal analysis. An abnormal nuchal translucency finding was observed in 59 fetuses. The sonographic diagnosis was confirmed after delivery or at postmortem in 90 cases. Ten fetuses had a cardiac anomaly which differed from the anomaly suggested by sonography. In the remaining cases, a postmortem examination was not possible because termination of pregnancy was performed by dilatation and curettage. In four cases we did not detect the cardiac anomaly in early pregnancy. Two of them were detected at rescanning in mid-pregnancy. Conclusion: Early detection of fetal cardiac anomalies is now possible. Most anomalies occur in low-risk pregnancies. We suggest performing a detailed early multidirectional dynamic continuous sweep ultrasound examination of the fetal cardiovascular system in all pregnancies.