Ultrasound in Obstetrics
In medicine, ultrasound is the use of high-frequency sound waves to create an image of a structure inside the body. Sound waves are produced by a hand-held device, called a transducer. A clear, water-based gel is applied to the skin. The gel conducts sound waves through the skin. To obtain images, a technician moves the transducer across the skin over the target area. The sound waves pass through the skin and echo, or bounce, off the tissues inside the body. A computer analyzes the pattern of sound waves as they are projected back to the transducer, and based in that information, produces an image.
Ultrasound for medical applications first became available more than 40 years ago. But it wasn't until the mid-1970's that hospitals slowly began accepting the equipment. Since then, the technology has come a long way. Grayscale (B-Mode) ultrasound is still in use today. The technique produces a two-dimensional image in shades of black and white. An advancement of the technology is Doppler ultrasound, which uses audio sounds to measure blood flow through an artery or vein. More recently, researchers have developed software programs which reconstruct ultrasound measurements taken from various angles – producing a three-dimensional image of an internal structure.
Ultrasound has many different medical applications. In the field of obstetrics, the technique can be used to give doctors a look at the fetus. The information can help determine fetal age, position of the fetus, placement of the placenta, and many types of structural abnormalities or birth defects. It can also be used to confirm the presence of more than one fetus and to monitor the fetal heart rate.
4-D Ultrasound for Obstetrics
Ultrasound can provide invaluable information for physicians. But there are some limitations to the techniques. The traditional gray scale ultrasound produces only a two-dimensional image, so doctors must depend upon their experience to create a three-dimensional mental picture. Depending upon the position of the fetus, it can be difficult to get images from certain areas of the body.
With three-dimensional ultrasound, doctors can get some very detailed images of fetal features and structures. The reconstructed image is stored on a computer and can be manipulated or turned to provide even more information. The addition of color imaging allows doctors to obtain images of fetal blood vessels in many areas of the body.
The main limitation of 3-D ultrasound is the production of a still image. Now, researchers have added a another dimension to 3-D technology – real time imaging. Instead of a static image, technicians can obtain pictures of fetal movement as it happens. The system also produces higher quality images, providing exquisite details of fetal features and movement.
Currently, 4-D ultrasound is still in its infancy and researchers and technicians are still learning how to get the most out of the technology. It may be useful in providing detailed functional information about the fetal heart and other internal organs.
4-D ultrasound is produced with the GE Voluson 730 Ultrasound System, which is available at nearly 200 hospitals and physician's offices throughout the country. The technology may also be useful to detect certain types of cancer, or to differentiate between benign and malignant tissue.
Ultrasound in Obstetrics