Abnormal or unusual? Discovering grey areas of prenatal screening

Congenital anomalies, which affect approximately 2% of all newborns worldwide, are responsible for perinatal mortality and long-term disabilities. Prenatal detection of congenital anomalies allows for informed decision making during pregnancy and improves neonatal outcomes. The Netherlands has a national prenatal screening program that offers various tests to detect both chromosomal and structural anomalies. These tests encompass the non-invasive prenatal test (NIPT) as well as ultrasound examinations conducted in the first and/or second trimester, where among numerous other aspects the nuchal translucency is assessed.
This thesis studied several grey areas of prenatal screening and tried to clarify some unusual findings with emphasis on cardiac anomalies and first-trimester screening. Topics such as: the sensitivity of ultrasound scans in first and/or second trimester, the relation between congenital heart defects and premature atrial contractions, the timing of surgical intervention after the prenatal diagnosis of a right aortic arch, the implications of an early increased nuchal translucency, the value of ultrasound in pregnancies with inconclusive NIPT results and the financial contribution as reason to opt out of prenatal testing.
This thesis concludes that prenatal screening aims to provide expectant parents with reproductive choices and to reduce neonatal mortality, however, the rapid advancements made in the recent decades have not only brought answers but also uncertainties. To differentiate abnormal findings from unusual ones, ongoing scientific research is necessary.