How Safe Is 4d Baby Scan?

4D baby ultrasound scan is safe. That is the long and short of it. Whilst that is actually true, nobody is going to take any such gospel-type pronouncements seriously. And rightly so. That is why I will try to explain this statement in this short piece.

Medical ultrasound has been with us for well over 60 years; that is since the 1940s when first used by Karl Dussick in Austria. It has been a mainstream investigative and diagnostic tool in pregnancy care since the 1970s and it is often described as an extension of an obstetrician?s hand. That is how dependent we have become on this technology.

Mainstream 3D and 4D ultrasound scan is largely a 21st century development. Whilst the technology has been around since at least the early 1990s, it has been almost exclusively a research tool, the computing power and huge cost being the main limiting factors. Computing power has increased exponentially, something that has allowed the cost to drop to realistic levels for the technology to come into the sphere of the ordinary consumer.

In the last 5 to 6 years, the use of 3D and 4D ultrasound scan in pregnancy has taken off at an astonishing rate all across the globe.

What is it?
First things first. It is important to make it clear from the outset that 3D and 4D ultrasound is exactly the same technology as the conventional 2D ultrasound that everybody is familiar with.

Ultrasound is basically very high frequency sound waves. These sound waves are at a frequency well beyond the perception of the human ear and therefore no sound is actually audible.

Conventional ultrasound gives an image in two dimensions. 3D ultrasound, as the name suggests, gives a three-dimensional image. However, as is the convention, 3D describes a static image. With this technological development, you can see the baby in 3D and see the motion as well. It is the motion that is described as the fourth dimension hence the term 4D. In other words, you can see your baby in three dimensions and see all the action taking place in the womb. Some examples here:

What is new?
A scanning machine is basically a computer. At its core is a processor that is supposed to interpret the reflected high frequency sound waves into a picture. It had hitherto not been possible to get a picture in 3D as well as real-time movements. This was simply beyond the computing power of a standard hospital scanner. However, with the massive increase of the computing power, this is now possible and affordable.

4D scan baby images are simply amazing, there is no argument. It is difficult to describe the emotional impact of this visual interaction with the unborn baby. There are quite a lot of scientific studies on the bonding effect of this type of scan and evidence is strong. Some of those scientific papers have been summarized (for the general public) at this link:

On the strictly medical front, 4D baby scanning has so far not proved to be significantly superior to conventional 2D scans in the diagnostic arena. This is why you are unlikely to see 4D scans replacing 2D scans any time soon. There is simply no compelling case for them yet in that area.

That brings us neatly to where we started. Is it safe? A 4D scan is as safe as the conventional 2D scan. Ultrasound scans, unlike X-rays or CT scan, do not employ any form of radiation.

The only theoretical risk is that of raised temperature. It is a well known scientific fact that the sound waves do cause a rise of temperature in the tissues where they pass through. The rise in temperature is dependent on acoustic power and scan duration. All modern scanners display what is known as a Thermal Index (TI). The index tells the operator about any change in tissue temperature. It is displayed continuously on the screen and therefore the operator stays within the accepted safe Thermal Index range.

There is solid evidence that elevation of temperature by 1.5?C above normal (37?C) is perfectly safe. In practice, this is rarely reached. It is also true that, in theory, the tissue temperature needs to rise to about 41?C to have the potential of causing harm. It is virtually impossible to reach this temperature in regular pregnancy ultrasound scanning.

In summary, apart from this visual evidence, it is known that the acoustic outputs produced by regular B-mode ultrasound are NOT high enough to produce harmful effects. The same is true of 3D/4D ultrasound.

A mother going for a 3D/4D ultrasound baby scan can look forward to a breathtaking experience at ease in the secure knowledge that she is not causing harm to her baby.

About the Author:

Dr Joe Kabyemela, MD, MRCOGObstetrician & Gynaecologist: Aintree Centre for Women?s Health; University Hospital Aintree and Liverpool Women?s Hospital.

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