Having a Third Trimester Baby Ultrasound in Sydney (Growth Scan)

This is a scan that you will have at 20 to 40 weeks, using a transabdominal ultrasound.  Not all women need to have an ultrasound in the later part of the pregnancy.

This scan is usually requested for the following reasons: baby is too small or too big, baby’s welfare is of concern, twin pregnancies, bleeding problems in pregnancy, placental location check, various medical problems eg high blood pressure, any reason necessitating for growth monitoring and follow up.

Transabdominal ultrasound

This ultrasound is done ‘transabdominally’, which means scanning through your lower abdomen.

A small amount of ultrasound gel is put on the skin of your lower abdomen, the ultrasound probe scans through this gel.

How to prepare for your ultrasound – to get the best results

Better images can be achieved when your bladder is a bit full.  So please empty your bladder one hour before your appointment, then drink two glasses of water and do not empty your bladder again until after your scan.

Your bladder should not be that full that it causes you pain. If your bladder is very full and painful, you should empty a small amount so you are more comfortable.

What to do if you feel faint during your scan?

Please tell the sonographer if you begin to feel faint or nauseous during our scan.  This is nothing to be alarmed at.  This feeling is due to a fall in your blood pressure, caused by compression of the veins that run at the back of your abdomen by the uterus and baby, thanks to your uterus being larger and heavier.  Your position can easily be changed, lying more on your side or more upright will usually help resolve your symptoms.

What do we look for during this baby ultrasound Sydney?

We assess growth and wellbeing parameters of the baby eg the head, abdomen, thigh bone, fluid around the baby, placental function using Doppler studies, foetal movements, rule out evolving structural problems in the brain, heart, abdomen and kidneys.

The growth parameters can give us a good estimation of the baby’s weight which can be compared to standardised charts.

More specialised investigations can be done if growth problems are encountered and one of our doctors will counsel you and your referring doctor will be notified.


3D / 4D images on the third trimester ultrasound

Our sonographers will endeavour to do 3D/4D images during this scan whenever possible.

As your baby is now bigger, the ultrasound now focuses on a part of the baby at a time, rather than the whole baby.  So, it can be more difficult to understand what you are looking at.  When focusing on your baby’s face, you may have a beautiful, clear image.

Many factors influence what parts of your baby can be seen and how well. These factors include the position of your baby, the volume of amniotic fluid (low fluid makes it harder to see) and the size of your abdomen (increasing skin thickness makes it harder to see).

To achieve good 3D/4D images may be occasionally difficult or impossible. Some babies press against the wall of the uterus or placenta, or they may have their arms or hands lying in front of the face.  Where we can we will endeavour to achieve the best images possible.