Fetal Chromosomal Screening

First Trimester Screening for Chromosomal Disorders: Nuchal Translucency According to Fetal Medicine Foundation Guidelines and Fetal DNA Testing from Maternal Blood

First trimester screening is a critical phase of pregnancy that assesses the risk of chromosomal disorders in the fetus, such as Down syndrome (trisomy 21), Edwards syndrome (trisomy 18), and Patau syndrome (trisomy 13). This non-invasive screening combines various analyses to provide an accurate risk estimate.

One of the primary tests is the measurement of nuchal translucency. This ultrasound measures the thickness of the fluid behind the fetus’s neck, a parameter that can be associated with the presence of chromosomal abnormalities. This examination is performed between the 11th and 14th weeks of pregnancy and must adhere to the strict criteria established by the Fetal Medicine Foundation, an organization that has developed international standards for evaluating nuchal translucency. When the measurement exceeds the normal range, the risk of chromosomal abnormalities may be increased.

In addition to nuchal translucency, there is now an additional option: fetal DNA testing from maternal blood. This test analyzes the circulating free fetal DNA in the mother’s bloodstream to identify potential chromosomal anomalies. The test is highly accurate and non-invasive, reducing the need for more invasive procedures such as amniocentesis or chorionic villus sampling.

By combining these tests, first trimester screening provides an early and precise assessment of the risk of genetic anomalies, allowing parents to make informed decisions regarding pregnancy management.