pregnant women getting an ultrasound
Louise Broadbridge
Louise Broadbridge

Ultrasound scans explained

Having an ultrasound scan is something most pregnant people look forward to. It is a chance to get a look at your baby in the womb and even get a picture you can show your family and friends.

Scans can make your pregnancy feel more real but they can also be a little nerve-wracking. Some women feel nervous about their scans in case they show there is a problem with the baby, especially if they have had issues in previous pregnancies or experienced a miscarriage or stillbirth.

How many scans will I have?

During your pregnancy, you will be given ultrasound scans to check on your baby’s development and wellbeing. In the UK, all expectant mothers are offered two routine scans during their pregnancy – the first at around 12 weeks and the second at 20 weeks.

You may also be given extra scans if it is medically necessary. For example, if you experience bleeding or have had miscarriages in the past, you may be offered an early pregnancy scan. You may also be offered additional scans in later pregnancy if there are concerns about the baby’s growth and development.

It is also possible to choose to have a private ultrasound scan if you want to get a closer look at your baby or find out their gender before 20 weeks. Many parents-to-be now choose to pay for 3D or 4D scans, which aren’t offered on the NHS. Make sure you shop around though as costs vary and make sure you understand exactly what you are paying for before you book.

How do ultrasound scans work?

Ultrasound scans are a non-invasive examination which hospitals use to look at internal body structures. They use high frequency soundwaves which bounce off the organs inside your body and your baby. 

The echoes created are used to create images and this means the sonographer can see your baby while they are in your womb. This allows them to look at their development, take measurements and check for any problems.

Ultrasound scans are considered safe during pregnancy but if you have any concerns, please speak to your midwife.

What will happen during a scan?

When you go for a scan, you will usually go into a small room and lie down on an examination table or bed. Some gel will be put onto your stomach and then the sonographer will place a probe known as a transducer onto your skin.

During the scan, this probe will be moved around your abdomen and at times it may feel like it is being pushed quite firmly into your skin – this is nothing to worry about, they are just trying to get a clear image of your baby.

You may be asked to attend your scan with a full bladder – this is because when your bladder is full, your uterus tilts backwards making it easier to get clear images. This can make the scan a little uncomfortable though and you may want to dash straight to the toilet as soon as they finish.

Most hospitals will print off images from your ultrasound scan if you ask but you will usually have to pay a small fee. You will usually be able to take an adult with you during the scan, although the policies at hospitals do vary so check what their rules are about being accompanied.

What is the 12-week scan for?

The 12-week scan is also called the dating scan and it is used to accurately date your pregnancy based on the size and development of your baby. It can be carried out any time between 10 and 14 weeks and you will be given a new estimated due date after the scan.

This may be the same as the date your midwife worked out from the dates of your last period but it is often slightly different. This new estimated due date will be the one used from now on for the rest of your pregnancy.

The sonographer will check the baby is growing in the right place and that they are developing as expected. If you are expecting more than one baby, you will usually find out during this scan, unless you needed to have a scan earlier on in your pregnancy.

If you have agreed to the nuchal translucency test to screen for Down’s Syndrome, this will be carried out during the scan. The sonographer will measure the amount of fluid at the back of your baby’s neck and this measurement, along with the results of a blood test, will be used to calculate the likelihood you might be expecting a baby with Down’s Syndrome.

What happens during the 20-week scan?

Known as the anomaly scan, this second routine scan is carried out between 18 and 21 weeks of pregnancy. This scan is a longer and more detailed examination than the dating scan.

Many parents-to-be look at this scan as their chance to find out their baby’s gender. Most sonographers will tell you the gender if you ask and they are able to see it clearly but this is not the medical purpose for the scan.

The sonographer will be checking your baby’s organs, including their heart and kidneys, as well as their bones, spinal cord, face and abdomen. They will also specifically look for signs of certain genetic health conditions and check the position of the placenta.

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