Ultralyd – Ofte stile spørsmål (FAQ)

Read about: Ultrasound main pageUltrasound week by week  | Foetal Diagnostics


On this page we have collected frequently asked questions and answers regarding ultrasound and examinations. 

When is the earliest we can get an ultrasound?

Already from weeks 6–7 we can perform an ultrasound and see if the heart beats.

Before 6 completed weeks (7+0), the foetus is not sufficiently developed and we cannot, therefore, expect to see a heartbeat. Just a couple of days play a major role in this context.

What happens if a missed abortion (MA) is detected at an early ultrasound?

Sometimes it happens that we do not see cardiac activity. This is usually due to a chromosomal abnormality.

We measure the embryo and refer the woman to the hospital she belongs to. Normally she will get an appointment in a few days. There, a gynaecologist will confirm the finding and a surgical or medical abortion will be performed.

The next day we send her a message to check in on her.

What is CRL?

CRL stands for crown-rump length. By measuring from the head to the bottom of the foetus one can calculate the age. The longer it is, the older the foetus. We can measure CRL already from week 6.

Is it necessary to have a personal health record card?

If the woman has a health card, we recommend that she bring it to all the examinations with us. There we can document what we have done and monitor how the pregnancy has been progressing.

Is it wise to eat something sweet before a 3D ultrasound?

No, we do not recommend this. If the baby is lying in a difficult position, you may want to eat something sweet or drink some cold water. This can awaken the baby so that it turns around and good images of the face can be taken.

When is the best time for a 3D ultrasound?

Between weeks 25–30.

Why can it be difficult to get good 3D images?

3D/4D ultrasound is recommended to do in weeks 25–30 as the conditions in the womb are most favourable these weeks. However, the examination can, regardless of the baby's age, be technically difficult. This is because several conditions must be present to create successful images. The result is therefore uncertain.

The starting point is a good 2D image. The baby must lie with his nose up, i.e. look up towards the mother's stomach. The baby must have amniotic fluid around the face and no arms or legs in front of the face. If the baby is facing the opposite way, with the face inward toward the mother's back or against the uterine wall, it won’t be possible to create a successful 3D image. It is like taking a picture of a baby with its back to the camera.

If the baby is in an unfavourable position, the woman must get up and move so that the baby can hopefully turn around and take good 3D images. If the position doesn’t change, you get regular 2D images. We will, nevertheless, make an estimation of growth, have a look at the organs and measure the amount of amniotic fluid. You will then pay for a growth scan.

What is a 3D ultrasound?

2D ultrasounds are the traditional ultrasound images reproduced in black and white and representing an incision through the body in one level or another.

With 3D, several of these cut images are superimposed. 4D is moving images.

Is ultrasound harmful?

Ultrasound of pregnant women has been performed for more than 30 years. No adverse effects on women or foetuses have been recorded.

In case of suspicion of illness or abnormalities, what happens next?

The midwives who perform ultrasound have completed one year of foetal diagnosis at the National Centre for Emergency Medicine at NTNU. If we see pictures that deviate from the normal we will refer the woman to a maternal-foetal medicine specialist at the National Hospital. She’ll then get an appointment within a few days.

What is growth measurement?

Growth measurement of the foetus can be done at any time during the pregnancy. When calculating weight, the due date set in the routine examination is used. Based on this, it is possible to see if the foetus’s weight is above or below average.

What is AFI?

AFI means Amniotic Fluid Index. We measure how many centimetres of amniotic fluid there is around the baby. If there is too much or too little, we refer the woman to the hospital.

Should you have an empty or a full bladder at the ultrasound examination?

The bladder should be empty.

Are you open in the evening and on Saturdays?

We are open until 9 pm, normally Monday an Tuesday. We are also open on some Saturdays.

When is ultrasound done internally (vaginal), and on the stomach (abdominal)?

We perform ultrasound vaginally early in the pregnancy, that is, from weeks 6–12. This is because the embryo is so small and the pictures become much clearer on an internal ultrasound.

The woman must lie with her legs in the leg holder with a towel over her. Most people have no problems with this.

Occasionally we also do an internal ultrasound in week 12. This is if the woman has a uterus that is turned slightly backwards or if she’s overweight.
In the case of a 3D ultrasound, the examination is done abdominally.

How long does the examination last?

The ultrasoundappointment last for 30 minutes.

What if the foetus is in the breech position, does that mean that the woman has to have a breech birth?

The foetus has plenty of room to move around in the uterus and it constantly changes position. It is not until the final part of the pregnancy that the position is important.

If the baby is in the breech position after week 36, we will refer the woman to the hospital for an examination. An X-ray of the pelvis is made to see if there is enough space for her to deliver in breech position.

If the woman does not want to deliver in the breech position, she will be given a caesarean section. Some doctors also try to turn the baby into a head-down position.

Can the due date change during the pregnancy?

When the woman comes to ultrasound early in the pregnancy, we can measure CRL and calculate an approximate due date. Foetuses grow at the same rate until week 23.

The final due date will be set around week 18 at the hospital where she will deliver, or here with us. This is the due date we take as a starting point for growth check ups later in pregnancy. It won’t be changed after this.

If the baby turns out to be small later in the pregnancy, it is not the due date that is wrong, but the baby who is growing slowly. We will then refer the woman to the hospital.

Who can come to the examination?

The woman usually has her partner with her. Sometimes she comes alone. We have had many relatives and friends at the examination and that’s very nice.

We do not recommend bringing small children as they tend to lose interest very quickly and disturb their parents. Older siblings, on the other hand, get great pleasure from being involved.