An ultrasound determines the thickness of the nuchal translucency
of the baby. This is a thin layer of fluid in the neck region. Also, the concentration of two hormones in the mother’s blood will be determined. In combination with the mothers age an individual chance of one of the three chromosomal abnormalities will be calculated. Every syndrome will have its own probability calculation. The combination test is safe for pregnancy and does not give an increased risk of miscarriage.

When: The measurement of the nuchal translucency can take place by ultrasound between week 11 and 14 of the pregnancy. The blood draw can take place between week 9 and 13.

Calculation of probability

The combination test gives a personal calculation of the risk that the baby has a chromosomal abnormality and has a 95% accuracy. Still, the scores are not exclusive; they do not give full certainty.

When the chance calculated is higher than 1 in 200 we speak of an enlarged risk. This risk leads to the offer of a secondary examination. The secondary examination consists of a Non-Invasive Prenatal Test (NIPT). If the score of this test is deviant, a chorionic villus test or amniocenteses is advised.


De combinatietest komt voor alle zwangeren die hiervoor kiezen voor eigen rekening (ongeveer € 163,-). Bij een verhoogd risico, danwel een medische indicatie wordt het vervolgonderzoek wel vergoed vanuit de basisverzekering.

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