2D ultrasound remains the basis of all obstetric and gynaecology imaging for diagnostic purposes. A recent development in ultrasound technology is the provision of 3D and 4D ultrasound imaging.

What is 3D ultrasound?

In standard 2D ultrasound imaging the picture seen on the screen is made up of thin slices of a particular area of your baby or pelvic organs. Only one thin slice is seen at a time, and although the sonographer can interpret this image it is often confusing for non-trained people. 3D ultrasound consists of a series of multiple 2D slices combined together to produce “life-like” pictures. No additional energy is required to generate a 3D image compared to a standard 2D image. Current evidence does not demonstrate any adverse fetal effects from this technology, however in obstetrics, the benefits of 3D/4D imaging over standard 2D imaging are not yet well-defined.


What is 4D ultrasound?

The term “4D ultrasound” refers to four dimensional ultrasound, the fourth dimension being motion (time). Ultrasound using 4D technology essentially shows moving 3D images (like a video). This “live 3D” technology may be useful in assessing the fetal heart and fetal behaviour.


Why offer 3D or 4D ultrasound?

The basis of ultrasound diagnosis in obstetrics and gynaecology resides with classic 2D ultrasound imaging techniques.

In gynaecology imaging, 3D ultrasound is of particular use in the demonstration of abnormalities of uterine shape or internal pathology such as polyps of the endometrium (lining of the womb).

In obstetric imaging, 3D ultrasound can refine the 2D diagnosis of a fetal problem such as a facial cleft lip or a club foot. This can assist parents in understanding the nature of a problem if one is found. More often, 3D ultrasound is used to demonstrate the fetal face for parents with greater clarity than 2D facial pictures of the normal fetus. The addition of motion (4D) can be of assistance in viewing the fetal heart structures and fetal limb motion. The demonstration of fetal behaviours (eg. Yawning, smiling, eye opening) can be a profound bonding experience for parents.


Can I always see a 3D picture of my baby?

Although we usually can obtain nice pictures of your baby with 3D or 4D technology, this is not always possible due to fetal position, placental location or if you are overweight. The optimal timing for 3D/4D imaging is 22-26 weeks gestation when the fetus has some subcutaneous fat and the amniotic fluid volume is optimal. It is frequently very difficult to obtain satisfactory 3D images in the late third trimester.