2D, 3D, and 4D Ultrasounds: What’s the Difference?

All ultrasound modalities can help you get a glimpse of your baby, and most of them are used by medical imaging centers to make sure your baby is growing strong and healthy.

But the characteristics and the visual appearance of  these images can vary widely from one another: 

•  2D Ultrasounds

When you think about prenatal ultrasounds, you’re probably thinking of a 2D ultrasound. This technology is called 2D because it captures flat images of your baby, which are two-dimensional, black and white ultrasound pictures.

The 2-Dimensional Ultrasound modality is the original, classic sound wave technology safely used for decades by healthcare professionals to assess the well-being of your little one at any gestational stage.

2D  ultrasound is the most common of all three types of ultrasounds because it is an excellent screening device enabling medical providers to visualize your baby to calculate your due date, evaluate the internal anatomy, listen and measure the fetal heartbeat, just to name a few.

 A 2D ultrasound uses reflected sound waves to generate an image. Ultrasonic waves are first sent inside the body using a handheld transducer (the ultrasound probe) placed on your abdomen.

The ultrasound gel placed on the end of the probe amplifies this signal (consisting of ultrasound vibrations), and when the sound waves bounce off different fetal structures in the body, the transducer picks those signals or “echoes” back again to be repeatedly processed by the ultrasound machine.

A computer ingergated in the ultrasound system uses the strength of the echo to organize all that information and produce an image of your baby. While regular 2D gray scale ultrasound provides a limited amount of “lifelike” detail, it remains the gold standard and best modality to determine the gender of the baby.

•  3D Ultrasounds

Similar to 2D ultrasounds, 3D ultrasounds also safely use sound waves to create an image, but they employ more sophisticated computer software that transforms the two-dimensional ultrasonic signal into a still three-dimensional image of your baby.

Think of a 2D ultrasound as a “slice”(this is what you see by looking at a standard fetal profile view) while 3D ultrasound uses much more volumetric information to create a complete-lifelike picture,which is sonographically reproduced in 3 Dimentions.

To obtain all the necessary information to create this 3D image, sound waves are reflected at many different angles, and a computer program simultaneously combines all these 2D signals into a vivid 3D imagery. 

Pioneering software accurately reproduces the textures of your baby’s skin in a seamless picture. Millions of pixels provide high-resolution details, and the powerful processing takes place in real time – in other words, the machine generates a static 3D image immediately on the screen during your ultrasound session.

While 2D images simply show your baby’s internal organs and outline, 3D ultrasounds’ sophisticated operations can produce a static picture in full color that shows detailed facial aspects and expressions with a photo-realistic quality. You will be thrilled to see those exact, familiar features the day your baby is born!

•  4D Ultrasounds

Finally, 4D ultrasounds are capturing multiple three-dimensional images over short periods of time and produce a live, real-time streaming of those images on the monitor. Since 4D imaging adds the element of real time to the process, the time is treated as the 4th dimension.

In essence, 4D ultrasounds are transforming static 3D ultrasound pictures into a dynamic 4D full-motion video, which adds an incredible anatomical realism letting you observe what your baby is doing momentarily, without delay.

Scientifically, 4D ultrasounds acquire multiple sets of 3D volumetric data within a continuous time frame that are aligned chronologically. 4D ultrasounds also use advanced computer software to rapidly process enormous amounts of data to turn what was once a flat, 2D picture into a short, four-dimensional video of your baby in real-time.

Getting the chance to glimpse your baby moving in the womb is a fantastic experience and the most moving experience during your pregnancy.

With the added dimension of movement, 4D ultrasounds can be an incredibly bonding experience for expectant parents with their unborn little ones.

 Depending on what your baby is up to during the exam, you might be able to see them kicking, yawning or sucking their thumb. 

Recent technological advancements have enabled us the development of 4D ultrasounds producing videos up of up 40 frames per second or even higher – that frame rate is common in movies and video games!