Fetal echocardiographic screening in twins for congenital heart diseases.

BACKGROUND: Congenital heart disease (CHD) is the most common congenital disorder at birth. Yagel and colleagues's method of heart examination has been proved valuable in finding CHD prenatally in single pregnancies. The aim of this study was to analyze the frequency of CHD in twin pregnancies and the sensitivity of the method.

METHODS: A total of 1103 pregnant women with twins were enrolled in this study, including 127 cases with high-risk for CHD. Five transverse ultrasound measurements were used for fetal heart examination, including the upper abdomen view, four-chamber view, five-chamber view, pulmonary artery bifurcation view, and three-vessel view. In the fetuses who were diagnosed with CHD and whose parents requested termination of the pregnancy, autopsy of the fetal heart was performed after an abortion, and a blood sample was collected from the heart for chromosome evaluation. In the other fetuses, a close follow-up was conducted by echocardiography within one year after birth.

RESULTS: Antenatally, CHD was found in 12 twins, of which 4 were from the high-risk group (3.15%), and 8 from the low-risk group (0.82%). In 2 pairs of the twins, the two fetuses had a same kind of CHD (one pair had tetralogy of Fallot (TOF), another pair had rhabdomyoma). Another pair had different types of anomaly (one fetus had TOF, and the other duodenal atresia with a normal heart). Termination of pregnancy was performed in these three pairs and the autopsy of the fetal heart confirmed the ultrasound findings. In the other 9 pairs, CHD was detected in one fetus, and a normal heart in the others. In the cases who received chromosome evaluation, 2 had abnormal chromosomes. During the follow-up after birth, heart examinations confirmed the prenatal diagnosis in 7 of the 9. The diagnosis of CHD was missed antenatally in 2 pairs of twins. In both the cases, one fetus was normal, and the other was confirmed as having CHD after birth (small ventricle septum defect in one, and persistent open ductus arteriosus in the other). Thus, the total frequency of CHD was 16 (7.3/1000), which was similar to that in single pregnancies. The sensitivity of fetal echocardiography was 87.5% and the specificity was 100%.

CONCLUSIONS: The frequency of CHD is the same in twin as in single pregnancies. Systemic ultrasound scanning with five transverse views is effective in diagnosing fetal CHD in twin pregnancies.