Value of antenatal echocardiography in high risk patients to diagnose congenital cardiac defects in fetus.

Results of fetal echocardiography in 1062 high risk pregnant patients are described. It was performed before 28 weeks of gestation in 770 cases. These were 38 abnormal scans (3.6%). A fetal arrhythmia was diagnosed in 14 cases and structural abnormality of the heart in 24. Complete atrioventricular block was commonest (n = 12), structural heart disease associated in two of these cases. Other lesions identified were atrioventricular septal defect (n = 5), hypoplastic left heart syndrome (n = 4), ventricular septal defect (n = 4), Ebstein's anomaly (n = 3), coarctation of aorta (n = 2) and others (n = 9). Postnatal confirmatory echocardiography is available in a total of 993 babies including 36 of 38 abnormal cases. There were eleven neonatal deaths amongst babies with abnormal scans. Errors in interpretation were observed in six instances. An anomaly was missed in five cases; in two of these, the main cardiac malformation was picked up but secondary lesions were missed. In one case, a false positive diagnosis of atrial septal defect was made. These errors did not influence the management of the pregnancy. Fetal echocardiography is a very sensitive (91.6%) and specific (99.9%) tool for antenatal diagnosis of congenital heart disease in high risk pregnancies. The information so obtained helps in guiding the optimal obstetric and neonatal management of these cases.