The combined test

The combined test is carried out early in the pregnancy to assess whether there is an increased chance that your child has Down syndrome (trisomy 21), Patau syndrome (trisomy 13) or Edwards’ syndrome (trisomy 18). The procedure is risk-free for you and your child.

When undergoing a combined test, you need to have a blood test done between 9 and 12 weeks of pregnancy, preferably a week before your appointment at SAM&, at the Amstelland Ziekenhuis (Hospital) or at another MDCA location. The concentration of two substances in the blood is measured (Beta hCG and PAPP-A). When there is a birth defect, the quantities of these two substances are often higher or lower than normal.

Nuchal translucency (NT) scan

The nuchal translucency (NT) scan takes place between the 11th and the 13th week of pregnancy. An ultrasound is performed where the thickness of fluid under the skin of the baby’s neck is measured. This layer of moisture is always present, also in healthy children. However, the thicker the fluid, the greater the chance is that the child has Down syndrome, or another chromosomal abnormality such as trisomy 13 and 18. In some cases, the increased nuchal translucency is an indication of another abnormality, for example, of the heart or lungs. The procedure takes between 30 – 40 minutes.

In some cases, when the image is unclear, an internal ultrasound is performed. The data from the blood specimen and the nuchal translucency (NT) scan are combined and processed by computer. You receive the results from your midwife, doctor or gynaecologist, mostly within a week.

When you come for a nuchal translucency (NT) scan, we need to know your weight, and the date of your blood test. To perform the ultrasound as well as possible, we ask you to come with a full bladder; urinate at home and then drink two glasses of water.

Neither the NT scan, nor the combined test are reimbursed. The costs for the procedure are € 170.13. You must pay by debit or credit card. Depending on any supplementary insurance you may have, it might be possible to place a claim retrospectively with your insurance company.

 

The result

The combined test takes the results of the blood test and the NT scan, together with the maternal age, to determine the risk of a child having Down syndrome, Patau syndrome or Edwards’ syndrome. The combined test does not establish with 100% certainty that your child has the syndrome of Down, Patau or Edwards’. This test only provides information over the possibility that a child may be born with the syndrome of Down, Patau or Edwards’. The risk is accurately calculated with the use of a special computer program. Your midwife, doctor or gynaecologist will receive the results usually within one week.

You can read more information about the combined test on the RIVM website.

The information can be downloaded in various languages
 

Non-Invasive Prenatal Test (NIPT)

The commencement of the NIPT-study on 1 April 2014, means there is an extra examination possible for a prenatal screening for Down syndrome and trisomy 18 and 13. The NIPT is performed at the Centrum voor Prenatale Diagnostiek (PND – Centre for Prenatal Diagnostics). This cannot be done at SAM&.

How does the test work?

The NIPT is a blood test which does not carry a risk of miscarriage. Neither, however, does the test provide 100% certainty. Overseas studies show that the test gives the following detection rates for pregnant women where a combined test showed an increased chance of having a child with Down syndrome, trisomy 18 and 13:

• More than 99 in 100 of unborn children with Down syndrome
• 97 in 100 of the unborn children with trisomy 18 (Edwards’ syndrome)
• 92 in 100 of the unborn children with trisomy 13 (Patau syndrome).

The NIPT makes use of a technique in which the blood of the pregnant woman is used to examine the DNA of the fetus. The test used is referred to in scientific research as ‘massive parallel sequencing’. This is a technique where the nucleotide sequence of many pieces of fetal DNA circulating in the maternal plasma are investigated simultaneously. By analysing and quantifying the origin of the DNA fragments per chromosome, it is possible to indicate an extra chromosome 21, 18 or 13.

The blood test is carried out at a time (from the 10th week) agreed between the pregnant woman and the doctor. The result is available within 10 to 15 work days. Because there is still a chance that an invasive test (chorionic villus sampling or amniocentesis) is needed, it is recommended that the NIPT is planned as early as possible.

Sensitivity of the test

The NIPT fails for 3 in 100 women. There are several reasons for this. One being that there is not enough fetal DNA present in the maternal blood. If this is the case, the pregnant woman can choose to have the test redone or undergo an invasive test. This depends on her personal situation and duration of the pregnancy.

Result

By a non-abnormal result, no follow-up examination (invasive test) is advised: the chance that a child has a trisomy is very small (less than 1 in 1,000). When there is an abnormal result, it is important to have a chorionic villus sampling or amniocentesis if there is any question of terminating the pregnancy. It could be that the child does not have a trisomy.

12-week ultrasound

• We offer the '12 week ultrasound scan upon request' for clients who do not want information about Down's, Edwards and Patau Syndrome, or for those who have already received this through the NIPT.

We will look at serious abnormalities during this scan.
• The '12 week ultrasound upon request' will be performed at a gestational age of 12 to 14 weeks, but preferably during the actual 12th week.
• The ultrasound operator will inform you and your midwife or doctor is he or she sees or suspects any abnormality.

• The '12 week ultrasound scan upon request' will take 20 minutes, will be at your own expense and will cost: € 67,50. You can only pay this amount by debit of credit card.

 

 

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In the Amstellandziekenhuis
route C geel
Laan vd Helende Meesters 8
1186 AM Amstelveen
Tel.: +31 (0)20 - 6400810