The Diagnostics of Fetal Heart Defects in the First and Early Second Trimester – Early Fetal Echocardiography

Abstract

Examinations of the fetal heart are increasingly being conducted as part of first-trimester screening, either as a sole visualisation of the four-chamber view or a visualisation of the four-chamber view and both ventricular outflow tracts or as a segmental approach as part of complete fetal echocardiography. Alongside anamnestic risks, markers for heart defects that become apparent during a first-trimester screening, such as thickened nuchal translucency, an abnormal blood flow velocity profile in the ductus venosus and the presence of tricuspid valve regurgitation, are indications for an early echocardiogram in this high-risk group. However, heart defects most often occur in fetuses in a low-risk group who display none of the markers mentioned. An increasing number of examiners are therefore also conducting a fetal echocardiogram as part of the detailed first-trimester screening of fetal organs. Up to 80 % of severe heart defects can be diagnosed as early as the 12th and 13th weeks of gestation. Apart from the examinerʼs experience and the best possible equipment, prerequisites are a consistent visualisation of all cross-sections and connections following a strict protocol, including transvaginal approach in some cases, and, in very rare cases, during a repeat examination a few days later. Nevertheless, primarily due to the intrauterine development of some heart defects, a further echocardiographic examination should always be carried out in the second trimester, when the detection rate is up to 10 % higher.