How do prenatal genetic screening and diagnostic tests differ?
Screening estimates the chance of selected conditions, whereas diagnostic testing investigates particular disorders more definitively. Cell-free DNA testing in maternal blood is screening, not a final diagnosis. Options are discussed according to preferences, history and pregnancy stage.
Details
A positive screen needs interpretation
Screening can produce false-positive or false-negative results. A higher-chance result should be discussed with a specialist; chorionic villus sampling or amniocentesis may be offered before major pregnancy decisions.
Understand the limits
No test checks every disease or structural abnormality, and a blood test does not replace recommended fetal imaging. Sampling procedures carry small risks explained before consent. Screening and diagnosis can be accepted or declined after informed discussion.
Embryo testing before transfer is different
Genetic testing during IVF occurs before pregnancy for selected indications. It does not automatically remove the need for prenatal follow-up and testing. Mention inherited conditions or a previously affected pregnancy during counselling.
Related reading: What are the steps of IVF from stimulation to pregnancy testing?.