What is 4D Fetal Ultrasound?

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Two-Dimensional Ultrasound

Conventional ultrasounds are generated in two dimensions. Ultrasound images are created by using a probe called a transducer to detect sound waves emitted by body tissues. The transducer emits sound waves which effectively bounce against body tissues. Organs, bones, and other types of tissue generate echoes of different sound wave frequency, allowing the ultrasound unit to build up a picture of the orientation of different tissues inside the body as they are exposed to the transducer.

3D Ultrasound

The conventional two-dimensional ultrasound is a flat image, much like a photograph. A 3D ultrasound adds the dimension of depth to the picture, and provides prospective parents with a much more detailed image of their unborn child.

An additional advantage of the 3D ultrasound is that the extra detail and the depth of the images allows for more accurate diagnosis of certain disorders. In particular, heart defects can be detected with much higher frequency and accuracy with a three-dimensional ultrasound.

Ultrasound in 4D

A 4D fetal ultrasound is simply a 3D ultrasound with the additional fourth dimension of time. A series of 3D ultrasound images is used to build up a short animated clip, allowing prospective parents to see their unborn child alive and moving in the mother’s uterus.

4D Fetal Ultrasound Benefits

Fetal ultrasound in four dimensions has no more risk than a two-dimensional fetal ultrasound; however there are some benefits of the 4D fetal ultrasound that are not related to the procedure itself, as much as they are related to the effect on the parents of seeing their unborn child in so detailed a fashion.

Many parents say that seeing a 4D ultrasound helps make their unborn baby a real presence in their lives even before the birth, and helps them bond with the baby. For some pregnant women, seeing a 4D ultrasound is an extra inducement to adopt healthy lifestyle practices during pregnancy, while fathers-to-be say the 4D ultrasound helps them bond at a time when the mother-to-be tends to be more focused on and involved with the pregnancy.


Joseph Woo, MD. A Short History of the development of Ultrasound in Obstetrics and Gynecology

See 4D Fetal Ultrasounds at The Endowment for Human Development