How 3D 4D Ultrasound scans work

Most ultrasounds are routinely performed using conventional (2D) scanning. This is where the ultrasound beam scans through a thin slice of the woman’s body or the baby, and shows the image on a screen in 2 dimensions only. This type of ultrasound provides most of the clinically relevant information to the doctor.

In recent years, 3D still images and 4D moving imaging ultrasounds have become increasingly popular and readily available. With 3D ultrasound, a series of thin 2D slices is digitally reconstructed to give more life-like images. With 4D ultrasound, the added dimension is time, so that the 3D images appear to be moving in real time. The 3D/4D image usually appears a golden colour on the ultrasound screen, as this colour is easy for patients to look at and highlights features on the baby.

3D/4D ultrasound uses the same ultrasound beams as the conventional 2D ultrasound, with extra processing performed by the ultrasound machine computer. 3D/4D ultrasound is just as safe as conventional 2D scanning, with no evidence that it harms you or your baby.

There is some diagnostic role for 3D/4D ultrasound in obstetrics, although this is currently limited to a few particular conditions,

For example, parents may better understand an abnormality like cleft lip when they see their baby in a 3D image, for the image appears more life-like.

Usually such conditions are first assessed in detail with the conventional 2D ultrasound.