Objectives: The aim of this study was to compare the cardiac findings at 11 to 14 weeks' gestation with the second-trimester findings to evaluate the reliability of first-trimester echocardiography and the possibility of congenital heart disease evolution.
Methods: The database of our fetal medicine unit was searched for all patients who had undergone fetal echocardiography at 11 to 14 and 18 to 22 weeks' gestation from 2005 to 2010. In all of the antenatally suspected cases of congenital heart disease, the diagnosis was established conclusively by postnatal echocardiography, surgery, or autopsy.
Results: Among the 870 fetuses included in the study, 802 were considered to have no abnormalities on both examinations. Thirty-six cases had abnormal findings on both examinations, and 32 had discordant findings. Among the 32 discordant findings, 6 cases had a false-positive diagnosis of congenital heart disease on early echocardiography, and 26 had a different diagnosis. In 14 of these 26 cases, the diagnosis was slightly different on the second-trimester examination, or the defect misdiagnosed in the first trimester was a minor one. In 6 of the remaining 12 fetuses, a major congenital heart disease was missed on the early echocardiography. In 6 cases, the congenital heart disease developed or progressed in severity in the second trimester.
Conclusions: First-trimester echocardiography is feasible and seems to allow considerably earlier detection of major congenital heart disease. However, it should be kept in mind that although most forms of heart defects can be diagnosed early in pregnancy, some may develop and become apparent only later in gestation.