Window to the womb

Especially in 3D or 4D clarity. But aside from the emotional benefits, what are doctors looking for during these scans and what does changing technology mean for monitoring your baby’s health?

Words Gillian Klawansky

According to Dr Lou Pistorius, a foetal maternal medicine subspecialist at Mediclinic Panorama, a 4D scan is ‘a 3D scan with movement’.

While detailed pictures are generated through static 3D scans, a 4D ultrasound reflects movement, allowing doctors to measure blood flow and monitor the vascular movements in three-dimensional clarity.

Although 3D and 4D scans are generally used to show the parents a live multi-dimensional picture of their unborn baby, there are clinical and medical uses of 3D and 4D scans when the more commonly used 2D scan cannot give the doctor a specific view of the foetus.

A different picture

3D and 4D scans are done as part of the important 12- and 20-week scans, when foetal specialists assess the risk of foetal abnormalities.

‘But this is not the main purpose of these scans, as 2D scanning is mainly used to provide a cross-sectional look at whatever the doctor is checking for,’ Dr Pistorius explains.

‘The Doppler ultrasound is used to show movement – it translates movement into colour, which is helpful as it shows blood flow into the baby’s heart and in specific vessels. Generally speaking, it’s rare that a 3D or 4D scan would really be necessary, as doctors can usually see what they need towith a 2D scan,’ he adds.

However, it’s through the detailed pictures provided by 3D scans that volumes of information can be generated and manipulated to get a clearer image than a 2D scan can give – usually because of the baby’s position.

‘In some cases when there is a problem with the baby, 3D or 4D scans can also help demonstrate to the parents what the problem actually is, like a cleft lip, for example,’ explains Dr Pistorius.

3D ultrasounds can also provide additional insight into potential heart abnormalities, helping to identify structural congenital anomalies of the foetus during the 20-week scan.

The risks

While there has been debate around the use of 4D scans for sentimental reasons, with some experts arguing that prolonged exposure to higher-than-usual levels of ultrasound energy that isn’t medically necessary is potentially harmful, there’s little proof that ultrasound is harmful to the foetus.

‘The main concern is around patient expectation management,’ says Dr Pistorius. ‘Although 3D or 4D scans aren’t generally meant to be medical – aside from ensuring the baby is growing well – there is a possibility that the sonographer may detect problems with the baby. If that’s something parents don’t want to find out before the birth, they should avoid these scans. But such cases are unusual.’

12 Weeks

This scan helps doctors to see the baby’s physical make-up – that it has two hands, two legs, a heart, a brain, and so on. But what’s also useful here is the ability to measure the risks for chromosomal abnormalities and assess the mom’s risk of pre-eclampsia, helping to prevent 80% of cases of early pre-eclampsia.

20 Weeks

This scan basically determines, as far as possible, that all baby’s organs are in place and growing independently and well. It’s also used to determine the position of the placenta and the amount of amniotic fluid.

Ultimately, an expectant mom can have a healthy pregnancy without ever having a 3D or 4D scan. However, says Dr Pistorius, some countries are now promoting having a more detailed scan in the third trimester (at 32-34 weeks), looking at potential abnormalities and baby’s growth in a more detailed way than the average gynaecologist and obstetrician could do. Combining 3D and 4D scans with such detailed examinations may be the way forward, Dr Pistorius concludes.

Learn more

Watch this video to learn more about 3D and 4D scans.