First Trimester (Combined) Screen Down’s Syndrome Screen

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Formal name: First Trimester Screen [Pregnancy-associated plasma protein-A (PAPP-A), free beta human chorionic gonadotropin (hCG) as either free beta subunit or total hCG, and nuchal translucency (NT) ultrasound]
Related tests: Triple Screen or Quad Screen; hCG; Amniotic Fluid Analysis; Chromosome Analysis

At a Glance

Why Get Tested?

To assess the risk of a foetus having a chromosomal abnormality, such as Down’s syndrome (trisomy 21).

When to Get Tested?

Usually between 11 and 14 weeks of pregnancy.

Sample Required?

A blood sample taken from a vein in your arm. Measurement of nuchal translucency (NT) requires a special ultrasound examination to be performed.

Test Preparation Needed?

You may be requested to have a full bladder when having the nuchal translucency ultrasound performed. Having a full bladder when you attend for your scan usually makes it easier to see the baby clearly and measure the nuchal translucency.