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What You Need to Know about 3D Ultrasounds

Feb 12, 2022 | 3 minutes Read

All types of ultrasounds are simple medical procedures, otherwise known as scans. This involves high frequency sound waves transmitted through the body and then picked up on a screen.

During pregnancy, a device known as a transducer is used to move along the mother's abdomen and this sends sound waves via her abdomen and through her uterus. These sound waves bounce off the baby in the form of echoes. A computer picks up the echo messages and translates them into an image on the screen. As the baby moves and kicks, images can be seen on the ultrasound screen. These sound waves are very high in pitch and intensity and cannot be heard by the human ear.

Ultrasound is a painless and noninvasive procedure. However, as you may need to have a full bladder if you are in the early stages of your pregnancy, it can be a little uncomfortable.

What's involved in a 3D ultrasound?

Having a 3D ultrasound is not such a different process to having a 2D ultrasound, at least for the mother. However, although the procedures are much the same, they use very different levels of technology to provide very different images.

A 3D ultrasound takes thousands of pictures of the baby at one time. These are then translated by computer into three-dimensional images which are almost as clear as a real-life photograph. These still pictures of your baby mean that you can see your baby in three dimensions, rather than two.

There is a depth and shape to a 3D image, giving a clarity which is not as evident in a 2D ultrasound. This is because a 2D ultrasound sees through the baby to its internal organs and tissues. With a 3D and even 4D ultrasound, the baby's skin can be seen so there is more of a realistic shape and form to the images. This is particularly clear when looking at the baby's face and delicate features.

With 3D ultrasounds, both the transducer used to transmit the sound waves and the computer software are more advanced and complex. A 3D ultrasound is more expensive.

How are 2D and 3D ultrasounds different?

A 2D ultrasound takes image slices which can only be viewed by looking at one image at a time. Sound waves are sent to the baby and reflected straight back which means there is a rather flat, surface appearance to the baby. A 3D ultrasound involves taking thousands of slices in a rapidly occurring series called a volume of echoes. These send sound waves back at different angles, allowing for the characteristic 3D depth.

Once these pictures are stored and shaded by the computer, they can be seen on the screen as clearer, three-dimensional images. The width, height and depth of the baby and its internal organs can be seen very clearly. With 3D ultrasound the baby has a more realistic shape and form, with distinctly baby-type features. They look exactly as they would if they were already born, only smaller of course.

Parents need to rely less on their imagination with a 3D ultrasound. It's as if all the 2D images have been filled in and puffed out so the image is quite clearly a baby, rather than a grainy image on the screen.

What's the benefit of having a 3D ultrasound?

Although it's lovely to see the baby more clearly, there are no real health benefits to having a 3D ultrasound when compared to a 2D one. 3D ultrasounds have been available since the late ‘90s, and thousands of parents have elected to have this done.

Performing a 3D ultrasound requires a high level of clinical skill and expertise. Unlike a 2D ultrasound, a 3D ultrasound requires the transducer to be held still and steady while the sound echoes bounce back. They are then interpreted by the computer software. If you have had a 2D ultrasound previously you will find the imagery very different.

When is the best time for me to have a 3D ultrasound?

Generally, the recommendation is between 26 and 30 weeks gestation, unless otherwise suggested by your maternity care provider. By this time, there is sufficient fat under the skin to see the baby's facial appearance, rather than the supportive bony structure.

Some clinics claim that past 30 weeks of gestation, the baby's head is more likely to engage in the mother's pelvis so visualizing the face can be more difficult. But this really depends on the individual clinic and their own practice guidelines.

How long will it take to have my 3D ultrasound?

A 3D ultrasound tends not to take as much time to complete as a 2D. This is because the images are very clear, and they can be stored within the computer's hard drive for later use if necessary. Sonographers aim to finish doing the 3D ultrasound within 30 minutes of starting the procedure. This is to limit any potential side effects on the baby from being exposed to prolonged sound waves.

Why can’t I see more of my baby?

How much you see of your baby during the 3D ultrasound will really depend on the way they are laying. If your baby is facing outwards and there is enough amniotic fluid surrounding their face, then you will be in luck. You will be able to see their back, shoulders, bottom, and limbs.

If, at the beginning of the scan, your baby is facing away from the transducer, keep your fingers crossed that baby will move or rotate into a clearer position before the scan is finished. If your baby is curled up tightly, facing your back or has their hands covering their face, then you won’t be able to see much of their features.

The sonographer may suggest you get up and go for a little walk or have a cold drink, talk to your baby, or gently massage your abdomen. These strategies may help to encourage your baby to move into another position.

Options available at some 3D ultrasound clinics

You may be given the option of taking home photos or a video of your 3D ultrasound. Check with the receptionist when you are making your appointment if you need to bring a thumb drive with you. You may be able to take home some photos of your scan.

Benefits of having a 3D ultrasound compared to a 2D ultrasound

There are no definite medical benefits to having a 3D ultrasound; however, if an abnormality has been identified a 3D ultrasound may provide better visualization than a 2D. This may apply to issues such as a heart defect, cleft lip, or a neural tube defect. Because of this early detection and awareness, planning for birth, postnatal care and management can begin very early. It can also help parents to know what they may be faced with when their baby is born, rather than needing to rely on their imaginations and the explanations of healthcare professionals.

Some parents find that having 3D ultrasound helps them to bond with their baby before birth. Having a clear view of their baby's face and features, looking for family likenesses, knowing the baby's gender and being able to see their baby makes a big difference.

At the time of the 3D ultrasound, some parents choose to name their baby and see this as a unique opportunity to build early emotional attachment. Yet for others, they are happy to wait until when their baby is born to meet for the first time.

The information of this article has been reviewed by nursing experts of the Association of Women’s Health, Obstetric, & Neonatal Nurses (AWHONN). The content should not substitute medical advice from your personal healthcare provider. Please consult your healthcare provider for recommendations/diagnosis or treatment. For more advice from AWHONN nurses, visit Healthy Mom&Baby at health4mom.org.