How to test fetal chromosomes

Fetal chromosome testing can be divided into screening and diagnostic procedures. Screening includes maternal serum testing, also known as Down syndrome screening, or non-invasive prenatal testing (NIPT) using fetal DNA. The results of these tests indicate the risk of fetal chromosomal abnormalities. If maternal history or the above screening tests suggest a high risk of fetal chromosomal abnormalities, chorionic villus sampling (CVS) or amniocentesis with amniotic fluid aspiration can be performed between 11 and 13⁺⁶ weeks of gestation. If these time windows are missed, cordocentesis (umbilical vein puncture) is an alternative option. Samples of chorionic villi, amniotic fluid, or umbilical cord blood can then be analyzed to determine the fetal chromosomal status and confirm the presence or absence of chromosomal abnormalities.