3D ultrasound is a medical ultrasound technique,often used in obstetric ultrasonography (during pregnancy),3D ultrasound providing three-dimensional images of the fetus.

There are several different scanning modes in medical and obstetric ultrasound.The standard common obstetric diagnostic mode is 2D scanning.In 3D fetal scanning,however,instead of the sound waves being sent straight down and reflected back,they are sent at different angles.The returning echoes are processed by a sophisticated computer program resulting in a reconstructed three-dimensional volume image of the fetus's surface or internal organs,in much the same way as a CT scan machine constructs a CT scan image from multiple x-rays.

3D ultrasound machine was patented by Olaf von Ramm and Stephen Smith at Duke University in 1987.

Clinical use of this technology is an area of intense research activity especially in fetal anomaly scanning but there are also popular uses that have been shown to improve fetal-maternal bonding.4D fetal ultrasounds are similar to 3D scans,with the difference associated with time: 4D allows a 3-dimensional picture in real time,rather than delayed,due to the lag associated with the computer constructed image,as in classic 3-dimensional ultrasound.



Background and Risks
Although 3D ultrasound technology may be used on any part of the body,elective 3D ultrasound conventionally refers to 3D ultrasounds performed on pregnant women for the sole purpose of the woman to see her unborn baby,what the baby looks like,or to see whether the baby will be a boy or a girl.In the medical literature,these elective 3D ultrasounds are also referred to as keepsake ultrasounds,although this term is rarely used in the lay population and only sometimes used in the media.

The use of ultrasound imaging devices for producing fetal keepsake videos is viewed as an unapproved use by the Food and Drug Administration (FDA)."When ultrasound enters the body,it heats the tissues slightly.In some cases,it can also produce small pockets of gas in body fluids or tissues." Phillips [FDA Spokesman] says the long-term effects of tissue heating and of the formation of partial vacuums in a liquid by high-intensity sound waves (cavitation) are not known."Performing prenatal ultrasounds without medical oversight may put a mother and her unborn baby at risk," says Phillips [FDA Spokesman]."The bottom line is: Why take a chance with your baby's health for the sake of a video?" Fetal keepsake videos are viewed as a problem because there is no medical benefit derived from the exposure.Further,there is no control on how long a single imaging session will take or how many sessions will occur.FDA is aware of entrepreneurs that are commercializing ultrasonic imaging of fetuses by making keepsake videos.In some cases,the ultrasound machine may be used for as long as an hour to get a video of the fetus.

This article comes from:Wikipedia
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