Prenatal diagnostics - examination of the foetus

Prenatal diagnostics is used to obtain information about the health status of the foetus. Prenatal diagnostics can give information about the genetic characteristics of the foetus, for instance, about a hereditary disease or specific anomalies.

Ultrasound examination of a woman

What is prenatal diagnostics?

Prenatal diagnostics is used to obtain information about the health of the foetus and about its genetic characteristics. Prenatal diagnostics can be done by ultrasound examinations and tests on samples from the placenta or amniotic fluid (amniotest).

It is also possible to obtain information about the characteristics of the foetus by analysing a blood-sample from the pregnant mother.  The tests used are called non-invasive prenatal testing (NIPT) or non-invasive prenatal diagnostics (NIPD). Both tests analyse DNA from the foetus in a blood sample from the mother.

If you are entitled to and would like to have prenatal diagnostics, you should contact your midwife or doctor early in your pregnancy. They will be able to give information about prenatal diagnostics.  You will need a referral if you want to have prenatal diagnostics through the national health services.

Your decision about prenatal diagnostics

It is you, the pregnant mother-to-be, who decides whether you want to have prenatal diagnostics. If you want the examination, you will have to give your consent.

You (and your partner) are encouraged to find information about prenatal diagnostics before your first pregnancy check-up. If you do, it will be easier to ask questions during your check-up.

Your midwife or doctor will give appropriate, neutral information about prenatal diagnostics at the first consultation. The information will help you to decide what is right for you.

If you need an interpreter, you should inform about this when you book your appointment.

Right to information 

Prior to a prenatal diagnostic procedure, you and your partner have a right to information about the procedures. The purpose is to help you to decide whether you want the examination. The information will cover different aspects of the examination that is offered to you and possible consequences. You should be told about:

  • what the examination involves
  • what the examination could reveal and how soon you will receive your results
  • what will happen if the examination shows that your foetus could have a disease or anomaly, and the consequences such results could have for your foetus/unborn child, for you and for your family

When you have your results

If the examination indicates or shows that your foetus/unborn child could have a disease or anomaly, you will receive more information about:

  • the disease or anomaly concerned
  • whether you will need to undergo further examinations to confirm the diagnosis

your rights, the follow-up offered, and relevant support

You may be faced with dilemmas

You are encouraged to think about the possible dilemmas that you might have to face. Although most foetuses are healthy, some pregnant women will experience that the examinations will reveal unexpected information about their foetus, e.g. that it has a disease or a major or minor anomaly.

The results may also be inconclusive, and if so, you will have to undergo further examinations to have a final result or conclusion.

Possibility for ultrasound scan during pregnancy week 11 to 14

All pregnant women who are 35 or older on the expected date for the baby to be born (the due date) will be offered an ultrasound scan in pregnancy week 11 to 14 (11+0 to 13+6). It is offered through the national health services, and it is free of charge. Pregnant women with specific risk factors will also be offered this ultrasound scan.

The ultrasound scan in pregnancy week 11 to 14 will be offered to all pregnant women by 2022. However, it takes time to make the se service available to everyone. Most pregnant women will have the ultrasound scan at their local hospital.

The NIPT-test

All pregnant women who are 35 or older at estimated time of birth/delivery/at the expected date of term (the due date) will also be offered a blood test that examines whether the foetus could have an extra copy of certain chromosomes (NIPT for trisomy 13, 18 and 21). Pregnant women with specific risk factors will also be offered NIPT. NIPT is free of charge.

If you are pregnant and younger than 35 on the due-date, you can ask for NIPT at one of the authorised private clinics. You will be charged for this service.

Prenatal diagnostics for pregnancies with specific risk factors

Some pregnant women will be offered more extensive prenatal diagnostics at one of the fetal medicine centres.

You will have the right to prenatal genetic testing or ultrasound-examinations at one of these centres if

  • an ultrasound scan indicates anomalies in the foetus, or the NIPT-test indicates trisomy 13, 18 or 21
  • you have an increased risk of having a foetus or child with a serious inheritable disease or anomaly. Cystic fibrosis and spinal muscular atrophy (SMA) are examples of such diseases.  
  • you or your partner previously had a child or foetus with a serious disease or anomaly

You can be referred to a Fetal Medicine Unit and/or a Department of Medical Genetics by the primary health-care responsible for your pregnancy check-up and by the local hospital.

If you (and your partner) are in a particularly difficult situation and will not be able to handle the burden associated with care for a child with a serious anomaly or condition, you can be offered an ultrasound-examination in pregnancy week 11 to 14 and NIPT at your local hospital.

A right to genetic counselling if there is increased risk for serious inheritable disease in your foetus or child

You are entitled to genetic counselling if you know that there is a serious hereditary disease in your family or your partner's family, that could increase your risk of having a child with the same disease. The right to genetic counselling will also apply if you previously had a child with a serious disease or anomaly.

If you want genetic counselling, you will be referred to a university hospital with a a Department of Medical Genetics / Fetal Medicine Unit in your health region.

A healthcare specialist, normally a genetic counsellor or a specialist in medical genetics, will provide the counselling.

You will receive information about:

  • medical facts about the condition
  • the prenatal diagnostic procedure (s) that can be used to reveal whether the condition is present in the foetus
  • how long it will take to before you have the result
  • the likelihood of having a child with the condition
  • if the foetus or child is affected, how the condition will develop/progress
  • the treatment options that are available

The ultrasound scan in pregnancy week 11-14

The ultrasound scan in week 11 to 14 will be done by a midwife or a doctor. The scan will determine whether the foetus is alive, estimate its age and the duration of the pregnancy, and examine the body of the foetus (head, arms, legs, belly, etc.) to have information about its development. Most foetuses have a normal development.

The ultrasound examination will also show the number of foetuses. If there are twins, it will be important to determine whether they share the placenta. Twins with a shared placenta need special follow-up during pregnancy.

The ultrasound scan can provide early information about a certain serious conditions and anomalies in the foetus. It can also provide information about conditions in the foetus that should be followed up carefully during the pregnancy.

The nuchal translucency (nuchal fold)

Between week 11 and 14 of pregnancy, there is a collection of fluid under the skin on the foetuses' neck – a nuchal translucency.

If the nuchal translucency is larger than expected, it is possible that the foetus has a chromosomal anomaly, for instance, trisomy 13, 18 or 21.

Trisomy is a chromosomal anomaly. The foetus will have an extra copy of chromosome 13, 18 or 21. The most common of these is trisomy 21, also known as Downs syndrome.

The risk or likelihood of trisomy 13, 18 and 21 is determined by measuring the nuchal translucency and combining the measurement with other information about you and the foetus.

A large nuchal translucency can also be associated with other conditions, such as heart defects or certain genetic diseases. Foetuses with an increase nuchal translucency may also be completely healthy.

About the ultrasound procedure

The ultrasound examination is normally performed by moving a device on the skin over the belly, but an examination via the vagina will sometimes give a clearer picture.

The procedure does not hurt and will not harm the foetus. The entire procedure, including the information given by the midwife or doctor, takes 20 to 45 minutes.

If the ultrasound examination shows that the foetus could have trisomy 13, 18 or 21 or an anomaly, you will be offered other examinations, and referral to a fetal medicine centre.

If there are any signs of trisomy, it may be necessary to test a sample from the placenta or amniotic fluid, because the results of such tests can provide a diagnosis.

NIPT for trisomy 13, 18 and 21

A NIPT (non-invasive prenatal test) analyse DNA from the foetus in a blood sample from a pregnant mother. The purpose is to obtain information about the foetus.

In all pregnancies, DNA from the placenta will be present in the blood of the pregnant mother. Analysing DNA from the placenta in the blood sample can give information about the genetic characteristics of the foetus, because the placenta and foetus usually have similar DNA.

A NIPT is used to examine whether a foetus has specific chromosomal anomalies:  trisomy 13, 18 or 21. In some cases, NIPT may indicate an increased likelihood that the foetus has a trisomy. If so, you are advised to have an additional test, on a sample from the placenta or amniotic fluid to obtain a diagnosis.

Trisomy is a chromosomal abnormality. The foetus will then have an extra copy of chromosome 13, 18 or 21. These are known as:

  • trisomy 13 (Patau's syndrome)
  • trisomy 18 (Edwards' syndrome) 
  • trisomy 21 (Down syndrome) 

NIPT is most precise for detecting trisomy 21. Trisomy 13 and 18 are rarer than trisomy 21. The NIPT-test is risk-free for both you and your foetus.

NIPT is less precise in twin/multiple pregnancies.

Who will be offered NIPT

All pregnant women are allowed to have a NIPT-test to check if their foetus could have trisomy 13, 18 or 21.

Pregnant women who will be 35 years or older when the baby is due, pregnant women with specific risk factors and those that are in a particularly difficult situation, will be offered NIPT via the national healthcare service.

If you are offered NIPT though the national healthcare services, the blood sample will be obtained when you have your ultrasound scan in pregnancy week 11 to 14.

You cannot have a blood sample taken for NIPT before week 10+0 of your pregnancy.  

The health services are not allowed to offer NIPT to determine the sex of the foetus (unless you have an increased risk for having a foetus with a sex-linked disease, see below).

Who can offer NIPT?

Only service providers with an authorisation from the Norwegian Directorate of Health can offer NIPT and obtain blood samples for NIPT. The sample will be sent to a competent laboratory for analysis.

If you are 35 or older when the baby is due, you will be offered NIPT at your local hospital.

Health professionals working for service providers without the necessary authorisation are not permitted to obtain blood samples for NIPT.

Private health-care providers

Authorised private service providers can offer NIPT. Before the blood sample is taken, a midwife or gynaecologist will do an ultrasound scan to check that your foetus is alive, and to determine the number and estimate the age of the foetus(es)/pregnancy week. The scan will provide information of importance for the NIPT analysis.

This ultrasound scan is a simple procedure that will not provide as much information about the foetus as the more comprehensive ultrasound scan in week 11 to 14 (described above).

The NIPT that is offered by private healthcare services is not covered by the national healthcare system (it is not free of charge).

How long will it take to get the results from a NIPT analyses?

You will receive the results of your NIPT test within 10-16 days. Your doctor or midwife will contact you in the way that was agreed at the consultation.

The midwife or doctor will explain the results to you, how reliable/precise the test results are, and whether any further testing or examinations may be necessary.

In most cases, NIPT tests show no signs of trisomy in the foetus, and fulrther testing will not be necessary.

What happens next if NIPT shows that the foetus could have a trisomy?

In some cases, NIPT may indicate an increased likelihood that the foetus has a trisomy. If so, the advice is to have further examinations, such as a more extensive ultrasound scan, or an analysis of a sample from the placenta or amniotic fluid.

You will have the possibility of follow-up at a fetal medicine centre. Hospitals and clinics which offer NIPT have procedures for referring pregnant women to a Fetal Medicine Unit.

NIPT or NIPD for other medical conditions

NIPT to determine the sex of the foetus

You will be offered a NIPT to determine the sex of the foetus if there is an increased risk that you will have a child with a serious, hereditary sex-linked condition (linked to the X-chromosome). Sex-linked conditions will mainly affect boys.

If you are entitled to this test, you will often be aware of the sex-linked condition in the family, and the risk implied. Possibly, you had genetic counselling before you got pregnant. You will need a referral to a Department of Medical Genetics or a Fetal Medicine Unit.

The NIPT-test for determining the sex of the foetus is very precise, but it cannot show whether the unborn child will have the condition or disease.

If the foetus is male, you will be offered a test of a sample from the placenta or amniotic to know if the foetus has inherited the genetic alterations that causes the condition. A test of a sample from the placenta or amniotic fluid will give a precise answer.

If the foetus is female, no further prenatal diagnostic testing will be necessary.

NIPD for conditions linked to specific genes (bespoke NIPD)

You may be offered non-invasive prenatal diagnostics (NIPD) if there is an increased likelihood of you having a child with a serious hereditary condition which is linked to a particular gene.

In most cases, the genetic alteration, if present, can cause a serious disease.  NIPD could be offered if you or the child`s father have the genetic alteration in question (dominant inheritance) or if you both have it (recessive inheritance).

You will need a referral to a medical genetics' unit or a fetal medicine centre. You have a right to genetic counselling prior to the test.

NIPD has been developed for a number of serious hereditary diseases linked to a single gene. The Department of Medical Geneticss will know whether it is possible to offer you a NIPD instead of a test on a sample from the placenta or amniotic fluid.

The NIPD analysis normally must be “tailored" for the individual woman or couple.

Placenta test

A placenta test is an analysis of a sample of cells taken from the placenta. The placenta develops from the fertilised egg, and therefore reflects the DNA (genetic material) of the foetus. A placenta test can show whether the foetus has inherited a genetic alteration that has cause a serious disease or condition in you or your partner, or in your or your partner's families. The test can also show whether a foetus with an increased nuchal translucency has trisomy 13, 18 or 21.

The placenta test can provide a definitive conclusion or answer. 

Who will be offered a placenta test?

You may be offered a placenta test if:

  • other prenatal tests have shown that there is a high probability of trisomy in the foetus
  • you have an increased risk of having a foetus with a serious, hereditary disease or condition
  • the ultrasound examination detected anomalies in the foetus

If you need a placenta test, you will be referred to a Department of Medical Genetics or a fetal medicine centre. You will have information and counselling prior to the procedure.

A placenta sample can be obtained after pregnancy week 11, most often between week 11 and 14.

What does a placenta test involve?

Placenta samples can be obtained in one of two ways:

  • through the abdominal wall (transabdominal)
  • via the vagina through the cervix (transcervical)

An ultrasound examination will be used to determine the best way to obtain the sample. This will depend on the position of the placenta.

Under ultrasound guidance, a needle is inserted into the placenta through the abdominal wall. The needle is used to draw a sample of tissue from the placenta.

Alternatively, a sample of tissue from the placenta will be obtained by a small tool or needle that is inserted via the cervix.

The procedure may hurt a little. The experience of pain varies from one individual to another. For most women, the pain is similar to the pain experienced when a cell specimen is taken from the cervix.

Afterwards, you may be asked to wait 15 minutes before leaving the hospital. You may be advised to relax a bit more than normal for two to three days after the procedure. Normally, you will not need to be absent from work.

How long will it take to get the results?

The time required to do the analyses and get the result will depend on the genetic test that is done. Most of the time, the results will be ready in 3 to 7 days. Some analyses take longer.

You will receive information about the expected time required for the analysis either during your genetic counselling session or when the sample was taken. You will be informed about the result in a letter or by phone.

Exceptionally, the result of the analysis of the placenta sample is not accurate. In such cases - about two percent of the analyses - it may be necessary to double-check the result by a new analysis of a sample from the amniotic fluid (amniotest).

Are there any risks associated with the procedure?

Up to 0.5 percent of women who have a placenta test may experience complications caused by the sampling procedure, including miscarriage. Any miscarriage will usually occur in the first week after the sampling procedure.

Amniotest

An amniotest (amniocentesis) is an analysis of a sample of cells taken from the amniotic fluid. An amniotest can reveal whether the foetus has inherited a genetic alteration that has caused a serious disease or condition in either your family or your partner's family. The test can provide a definitive conclusion or answer, e.g.  whether or not the foetus has trisomy 13, 18 or 21.

An amniotic fluid sample will normally be obtained after the 15th week of the pregnancy, so a bit later in pregnancy than the placenta test.

Who will be offered an amniotest?

You may be offered an amnio test if:

  • other prenatal tests indicated that there is a high risk or likelihood of trisomy in the foetus (e.g. NIPT)
  • you have an increased risk of having a foetus with a serious, hereditary disease or condition
  • the ultrasound scan detected anomalies in the foetus

If you need an amniotic fluid test, you will be referred to a Department of Medical Genetics or a fetal medicine centre. You will have information and counselling prior to the procedure.

The amniotic fluid sampling procedure is normally performed between week 15 and 16 of the pregnancy.

What does an amniotest involve?

Prior to the amniotest, you will undergo an ultrasound scan to determine the size and position of the foetus, and to find the best place to insert the needle.

Under ultrasound guidance, a thin needle will be inserted into the uterine cavity. Approximately 15 ml of amniotic fluid will then be drawn. This procedure may hurt a little, much like having a normal blood sample taken.

Afterwards, you may be asked to wait 15 minutes before leaving the hospital. You may be advised to relax a bit more than normal for two to three days after the procedure. Normally, you will not need to be absent from work.

How long will it take to get the results ?

The time required to do the analyses and get the result will depend on the genetic test that is done. You will normally have the results within 7 to 10 days. Some analyses take longer.

You will receive information about the expected time required for the analysis either at your genetic counselling session or when the sample is taken. You will be informed about the result in a letter or by phone.

Are there any risks associated with the amniotest?

Up to 0.5 percent of women who have an amniotest may experience complications caused by the sampling procedure, including miscarriage. Any miscarriage will usually occur in the first week after the sampling procedure.

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