What is a dimension and the difference between 2D/3D/4D/HD?

How many dimensions are there in ultrasound?

In ultrasound, a dimension is defined as the measure of length. We live in a 3D (D stands for dimensional) world with the 4th dimension as time. By using multiple dimensions in ultrasound, we can find the width, depth and height of an object (in this case, your baby!). Below is short summary of each dimensions and how ultrasound takes advantage of it.

2D ultrasound

2D ultrasounds are the traditional “black and white” images typically seen and represent a flat cross section of your baby. These images allow you to see through the baby and their organs and skeletal system can be visualized. This is very useful for obtaining growth measurement, heart rate and detecting abnormalities.

3D/4D ultrasound

3D ultrasound uses multiple 2D image slices to create the “surface” of the baby this is the third dimension. This allows you see the baby from the outer skin surface instead of bones.

When the 3D image is combined with time (fourth dimension) this will show live 4D movement of the baby and allows you to view the baby in real life motion as they are occurring in the womb. Facial expressions such as a yawn or sucking the thumb or toe can be seen.

HD ultrasound

High Definition (HD) is the latest technology in rendering surface and is unlike anything you ever seen. Compared to the monochrome surface of the 3D images, HD images show real skin tone life like baby images with no additional cost.

What about 5D? Where does the next dimension come from?

That is a good question, the simple answer is no. There is no extra dimension used in ultrasound. For more information, please have a look at our previous blog.