When I fist taught about this 3-dimensional ultrasound was very much in the research and development stages. But over the past few decades faster and more advanced commercial models came into the market. The scans requires special probes and software to accumulate and render the images, and the rendering.

A 3D ultrasound, more technically known as 'phased array ultrasonics', is a medical sonography technique that was patented in 1987. While also useful for medical evaluation and diagnosis, it is most commonly used for obstetric purposes, specifically for capturing three-dimensional images of a foetus during pregnancy. During a sonography scan, high-frequency sound waves are sent inside the body. The sonogram machine then sends them back at different angles creating echoes that are translated into three-dimensional images.

Scan time has been reduced from minutes to fractions of a second. A good 3D image is often quite impressive and further 2D scans may be extracted from 3D blocks of scanned information. Volumetric measurements are more accurate and both doctors and parents can better appreciate a certain abnormality or the absence of a certain abnormality in a 3D scan than a 2D one and there is the possibility of increasing psychological bonding between the parents and the baby.

A large volume of literature and documentation has been published and the diagnosis of congenital anomalies could receive revived attention. At the beginning of the millenium evidence had already suggested that even small defects such as spina bifida, cleft lips/palate, and polydactyl may be more lucidly demonstrated by this technique. Other more subtle features such as low-set ears, facial dysmorphia or clubbing of feet can be better assessed, leading to more effective diagnosis of chromosomal abnormalities.

The study of foetal cardiac malformations has been valuable. The ability to obtain a good 3D picture is nevertheless still very much dependent on operator skill, the amount of liquor around the foetus, it's position and the degree of maternal obesity, so that a good image is not always readily obtainable.

Experts in this field have not considered that 3D ultrasound will be a mandatory evolution of our conventional 2D scans, rather it is an additional piece of tool like doppler ultrasound. It's greatest use is still in research and particularly in the study of foetal embryology.