ABSTRACT
WHAT IS ANTENATAL SCREENING? Antenatal screening is a process to assess the risk of an unborn baby (the fetus) having a congenital abnormality. Screening for neural tube defects was one of the initial routines in antenatal screening. Today, screening involves an array of biochemical and ultrasound tests, resulting in an increasing plethora of conditions that can be detected during early pregnancy. These conditions include Down’s syndrome, spina bifida, sickle cell anemia, thalassemia, HIV, and hepatitis B. A diagnostic test, usually invasive, such as amniocentesis or chorionic villus sampling, is in order when the risk is assessed to be above a predefined value. Noninvasive prenatal determination of fetal Rh and sex status using cell-free fetal DNA in maternal blood is now available in some countries (1). Prenatal diagnosis of single gene disorders using cell free fetal DNA obtained from maternal blood will be available in the near future (2,3).
