Prenatal screening

Prenatal Screening

During pregnancy, you can choose to undergo certain tests to learn more about your baby’s health. In the Netherlands, there are three main types of prenatal screening:

  • NIPT – A blood test that screens for chromosomal abnormalities

  • 13-week ultrasound (ETSEO) – Early screening for physical anomalies

  • 20-week ultrasound (TTSEO) – Structural anomaly scan

Below you’ll find more detailed information about each of these screenings.

NIPT (Non-Invasive Prenatal Test)

As of April 1, 2024, NIPT is the only available blood test for detecting chromosomal abnormalities. This test replaces the previous combination test. The NIPT examines the pregnant person’s blood, which contains DNA from both the mother and the placenta—usually matching the baby's DNA. From 10 weeks of pregnancy, a blood sample can be taken to screen for Down syndrome, Edwards syndrome, and Patau syndrome.

NIPT is a simple blood test: ✔️ Can be done after your dating scan
✔️ Blood is drawn from your arm
✔️ Our designated blood draw location is the VUmc, open Monday to Friday from 07:30 to 16:30 (no appointment required)
✔️ The lab analyzes your blood for chromosomal abnormalities

Results are available within 10 working days.
NIPT does not offer 100% certainty. Sometimes a condition may be present but not detected. If your result is normal, no further testing is needed. If an abnormality is detected, you may choose to undergo follow-up testing for confirmation.

Starting April 1, 2024, secondary findings—other chromosomal abnormalities in the baby, placenta, or rarely the mother—are routinely reported.

More info: www.pns.nl/nipt

13-Week Ultrasound (ETSEO)

This early anomaly scan is performed between 12+4 and 14+3 weeks of pregnancy. It aims to detect physical abnormalities at an early stage, such as anencephaly (open skull) or major abdominal wall defects. This is a medical scan, and participation is optional.

The 13-week and 20-week ultrasounds share the same purpose and complement each other. Some serious anomalies can already be seen at 13 weeks, but others become more visible at 20 weeks when organs (like the heart) are more developed.

If the sonographer sees anything unusual, early follow-up testing may be offered, giving more time for decision-making.

Important notes:

  • You must have a counseling session with your midwife and give written informed consent.

  • The scan is only available between 12+3 and 14+3 weeks. If you're unavailable during this period (e.g., due to travel), you cannot participate.

  • We schedule this scan after your dating scan.

  • The 13-week ultrasound is part of a national scientific study and is fully funded by the government.

More info: 13-week scan – PNS

20-Week Ultrasound (TTSEO)

Also called the structural anomaly scan (SEO), this ultrasound is used to detect physical abnormalities in the baby. These can include:

  • Spina bifida (open spine)

  • Anencephaly (open skull)

  • Hydrocephalus (fluid on the brain)

  • Heart defects

  • Diaphragmatic hernia

  • Abdominal wall defects

  • Kidney or skeletal abnormalities

About 5 in 100 pregnancies show something that may be an abnormality. It’s not always clear what it is, how serious it is, or what it means for the baby. If something unusual is found, you may choose to undergo further testing.

Timing:
The scan can be done between 18+0 and 21+0 weeks, but we recommend scheduling it between 19+0 and 20+0 weeks to allow time for follow-up diagnostics if needed.

This scan is covered by your health insurance.
More info: 20-week scan – PNS | RIVM website

Follow-up Testing at a Prenatal Diagnosis Center

If further testing is needed, it takes place at a Prenatal Diagnosis Center, such as the one at VUmc (location AMC). There, you will receive a detailed ultrasound, known as an advanced ultrasound exam (GUO). This scan is similar to the 20-week ultrasound but takes longer and uses more precise equipment. A fetal medicine specialist may also be present.

This exam is painless and safe for your baby.

Sometimes the doctor may recommend:

  • Blood testing – Your blood is analyzed in a lab

  • Amniocentesis – A needle is used to collect a small sample of amniotic fluid, guided by ultrasound to avoid the baby

Amniocentesis can be done from around 15 weeks. Results typically take 3–5 working days, but if more in-depth chromosome analysis is needed, results may take up to 2 weeks. The risk of miscarriage from amniocentesis is very small—about 2 in 1,000 cases.