A–Z Glossary

Down syndrome

A chromosomal condition caused by an extra copy of chromosome 21.

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Second trimester screening and quad screen test

Second trimester screening and quad screen test

What second trimester screening means Second trimester screening is a broad term for prenatal tests offered in the middle of pregnancy to refine the chance of certain fetal conditions. In practice, it often refers to maternal serum screening, sometimes combined with ultrasound. The quad screen is the most common blood-based option. It is called a […]