Different Ultrasound Types

Most people have heard of the word “ultrasound” and have some idea of its meaning. But unless you’ve actually had one or been with someone else who’s had an ultrasound, then it’s hard to imagine exactly what’s involved.

So let’s start at the very beginning and find out precisely what an ultrasound is and why they are sometimes necessary.

One of the primary benefits of an ultrasound during pregnancy is that it is non-invasive and provides a lot of information easily at a relatively low cost. It is also quick and gives a real time interpretation of the baby’s current experience.  And although the clarity of the images is often not cutting edge and sometimes quite grey and unclear, ultrasound remains one of our best options in terms of assessing maternal and foetal wellbeing.

Ultrasound images are like looking at an individual slice of bread, rather than seeing the whole loaf at the one time. Similarly, “slices” or images of the baby are seen on the monitor or screen, rather than the whole baby at once. And this is why at any one time when having an ultrasound, the baby’s head and face, and perhaps their arms are visible rather than their whole body. As the transducer is moved around the mother’s abdomen, different portions of the baby’s body become visible.

What is an Ultrasound?

Most types of ultrasound are a medical procedure which is done in a radiography clinic or within the X-Ray department of a hospital. It is a process which involves high frequency sound waves feeding back information which is then interpreted by a computer and a sonographer, a health professional who is trained in ultrasound practice.

A device known as a transducer contains a small vibrating crystal and from this, high frequency sound waves are emitted. These sound waves bounce off internal structures and different images are then reflected on the monitor screen, depending on the type of tissue the sound waves reflect from.  

The sounds, or echoes, help to create an image. Whilst not as clear as a photograph, they are often so lifelike that the 2D black and white images don’t need much interpretation at all.

The sound waves used are so high that they can’t be heard by the human ear and this is why the term “ultra” is used in the naming of the procedure.
Other names for an ultrasound are scan, or ultrasonography, or sonogram.  

How is an Ultrasound Done?

You will need to go to a radiography clinic which provides ultrasound services. Not all do, so make a point of checking first if you’re planning to just nip down to the X-ray clinic on your local corner. You will need to expose your belly, so preferably wear pants or a skirt so you do not need to uncover too much flesh.

Some special gel will be squirted onto your lower abdomen, in the region between your navel and your pubic bone. Most sonographers warm the gel in a bowl of water first, so there’s not so much of a shock when it meets with the skin.  This gel helps to reduce the friction and increase the contact between the ultrasound probe (also known as a transducer) and your skin, so that the images are clearer. This gel is a pale blue, translucent colour and is water soluable. So even if a small amount gets onto your clothing it will wash out easily and not leave a stain. The sonographer will also wipe off any excess before you re-dress to minimise any seepage onto your clothing.

The transducer will be moved across your tummy until a clear image becomes available and then the sonographer will hold it there temporarily. Generally, the sonographer will hold the transducer with one hand and with the other be typing information into the computer keyboard.

At times throughout the procedure they will pause, click on various keyboard options, fill you in on what they are doing and make some adjustments to the image. They will also take some “photos”, measure various distances and diameters your baby’s growth, and essentially do a summary of what they are looking at.

The procedure generally takes around thirty minutes, sometimes shorter and sometimes longer; it really just depends. Often, the position the baby is lying in determines how long the ultrasound takes. If the baby is being considerate and lying reasonably still in an optimum position, then all the necessary information is gathered seamlessly. But if the baby has decided to become very busy right at the same point of time the sonographer needs to do some careful measuring, then it becomes necessary to wait until things quieten down a little. Other factors which influence the quality of an ultrasound include: the mother’s weight, her stage of pregnancy, the skill of the sonographer and the quality of the equipment being used.

Why Would I Need to Have an Ultrasound?

An ultrasound is one way of being able to see what’s going on inside someone’s body. It gives a real life “picture” of their internal organs and structures without having to do an operation or any invasive procedure. Occasionally a special probe is used, such as with a vaginal ultrasound or a gastroscopy (stomach/gut scan). These probes are used to target the sound waves to a specific area.

Ultrasounds are commonly used during pregnancy to assess the growth and development of the baby. But they are also used for other, routine medical assessments as well. Areas such as the abdomen, pelvis, muscles, joints and event the heart and blood vessels can all be visualised through ultrasound.  

If there is a problem with a baby detected via ultrasound it is very useful to know about this as soon as possible. Planning, counselling and preparation for the birth and early post natal care can begin once ultrasound findings have been clarified. It also allows for parents to do some of their own research and feel that they have an element of control over their situation.

Reasons why Ultrasound is used During Pregnancy

  • To check that the baby is developing as it needs to.

  • To ensure the position of the baby and the placenta.

  • To check how many babies are present. Ultrasound is one way of diagnosing a multiple pregnancy, especially when a mother is large for her pregnancy dates and she or her maternity care provider become suspicious. 

Will an Ultrasound Hurt Me or My Baby? 

No, to the best of all available knowledge, ultrasounds pose no risk to a mother or her baby. Research has been conducted for many years into the potential risks of ultrasound to a mother and her developing baby but to date it is still considered safe.

Ultrasounds do not involve ionising radiation, so unlike X-Rays there is no risk of radiation complications. Occasionally, the procedure may cause some discomfort because a mother may need to have a full bladder. But this is only for a short period of time and if it becomes too uncomfortable, the sonographer will be able to redirect the transducer so there’s not as much pressure.

Will I Need to Drink Lots of Water?

If you are having a first trimester ultrasound, you may be advised to drink 750ml-1litre of water in the hour or so preceeding their ultrasound. This is because in the early weeks of pregnancy, the uterus lies deep in the pelvis and is covered by the bowel.  And the gas within the bowel does not allow the ultrasound waves to pass through.  Urine in the bladder helps to push the bowel away and also to “lift” the uterus up out of the bony pelvis.

For more information on the different types of Ultrasound, read the articles on 2D Ultrasound; 3D Ultrasound and 4D Ultrasound.

This article has been authored and provided to The Pregnancy Centre by Huggies Australia www.huggies.com.au


Demac Resources Pty Ltd December 2013 - 2020.