What's the difference between a 3D and 4D ultrasound?

3D Ultrasound 24 weeks
Photo © BSIP/UIG/Getty Images

Question: What's the difference between a 3D and 4D ultrasound?

About 70% of women will have at least one ultrasound done in pregnancy. As the newer imaging technologies become more widely available in ultrasound, you might hear various terms thrown around like 2D, 3D and 4D ultrasounds.

Answer: There are differences in the types of ultrasounds done in pregnancy. The old standard was a 2D or 2 dimensional image.

In recent years this has been replaced with the new 3D or three dimensional images and now 4D.

2D ultrasound give you outlines and flat looking images, but can be used to see the internal organs of the baby. This is helpful in diagnosing heart defects, issues with the kidneys and other internal issues. The 3D images are used to show you three dimensional external images which may be helpful in diagnosing issues such as a cleft lip. What 4D ultrasound brings to the table is that as the image is continuously updated, it becomes a moving image, like a movie.

Each of these types of ultrasound have advantages and disadvantages. Many families prefer the 3D images because they look more like what they perceive a baby to look like in real life than the flatter 2D images. You should talk to your doctor or midwife about type of ultrasound they use and why. 

Here are some examples of ultrasound photos:

There are also families who are not big fans of the 3D images, particularly in the early weeks of pregnancy. 

"When I saw the screen, I was expecting to see a little bean with some jumping pixels where the heartbeat was," explained Amanda, mother of two. "Instead it was this really weird and very alien looking image that really looking not right.

My husband and I kept asking if everything was okay. The person doing the ultrasound didn't understand why we were worried. Thankfully we had our appointment just after and could ask our OB if everything was okay. She figured out that it was the difference between the 2D and 3D that had thrown us off."

The Food and Drug Administration (FDA) does not recommend that you get ultrasounds done for fun or bonding purposes, citing the use of ultrasound as a medical technology. This means that you should avoid places that offer ultrasounds that are not recommended by your doctor or midwife in pregnancy.


3D/4D Ultrasound. WebMD.  http://www.webmd.com/baby/guide/3d-4d-ultrasound Last Accessed 9/1/2015.

American College of Radiology. PRACTICE PARAMETER FOR THE PERFORMANCE OF OBSTETRICAL ULTRASOUND http://www.acr.org/~/media/ACR/Documents/PGTS/guidelines/US_Obstetrical.pdf. 2014. Last Accessed 9/1/2015.

Avoid Fetal "Keepsake" Images, Heartbeat Monitors. Food and Drug Administration. March 28, 2008.

Wiseman, C, Kheil, E.  Picture Perfect: Benefits and Risk of Fetal 3D Ultrasound.  MCN, The American Journal of Maternal/Child Nursing.  April 2007, Volume :32 Number 2, page 102- 109.

Continue Reading