Genetics meets ultrasound: early prenatal screening for congenital anomalies

The present thesis aimed to study several aspects and implications of prenatal screening and diagnosis, with special emphasis on screening for structural and genetic anomalies during the first trimester of pregnancy. Chapter 3 shows the impact of the introduction of the Dutch Prenatal Screening program on the redistribution of perinatal mortality rates in fetuses and children with congenital anomalies. Chapter 2 and chapter 7 focus on the timing of diagnosis of congenital anomalies by ultrasound and demonstrate how the lack of first-trimester anatomical screening (FTAS) causes a delay in the diagnosis of severe defects. Subsequently, chapter 4 and chapter 5 present the additional value of the combined test (CT) (with nuchal translucency measurement) as screening for several types of congenital anomalies, including structural and rare genetic defects. In chapter 6 we discuss the role of ultrasound in fetuses with twice-inconclusive cell-free DNA results and finally, in chapters 8 and chapter 9 we address some less frequently studied aspects of FTAS implementation, namely maternal psychological wellbeing and quality standards of image acquisition by trained sonographers.