Also known as Diagnostic Dynamic Medical Imagingl Sonography, ultrasound uses high frequency sound waves to create an image of your internal organs. A colorized ultrasound is known as a Doppler. Ultrasound is the only modality besides MRI that does not use some form of ionizing radiation.
Lets start with the differences in the terminology. 2D means 2-Dimensional - meaning Length and Width, but not depth. 3D means 3-Dimensional - meaning Length, Width, and Depth. 4D means 4-dimensional - meaning Length, Width, and Depth over Time.
A 2D ultrasound refers to a regular, black and white sonogram. This examination provides you with an outline of the baby. While this technology has proven very useful, it's shortcoming is that it is often hard for parents, or anyone who does not frequently see ultrasound images to see their baby.
A 3D ultrasound uses the same basic concept of a 2D ultrasound, technology-wise, but rather than take the image from a single angle, the sonographer takes a "volume" image. The volume image that is displayed on the screen is a software rendering of all of the detected soft-tissue - meaning your baby's face, hands, feet, or whatever the sonographer happens to be focusing on. A 3D ultrasound produces a still image.
A 4D ultrasound (also referred to as "Live 3D") extends on the concept of a 3D ultrasound, but rather than taking a single volume image, multiple volume images are taken in rapid succession. The result of these images displayed in succession is a motion video of the baby. You can see movement, such as arm or feet movement, thumb sucking, and even smiling.
There is a lot of confusion surrounding this terminology. GE strongly marketed the term "4D Ultrasound", whereas other companies that make ultrasound machines with similar capabilities marketed the terms "3D ultrasound", "Live 3D", and others. The GE Voluson machines produce the clearest images and the smoothest video. Most of the high quality sample images you see on the internet were taken with a GE Voluson machine.
Ultrasound is an excellent diagnostic tool which is utilized in several different situations. Your physician may have referred you for this test so he or she could obtain an image or picture of your internal body structure. This test is very useful in examining the fetus during pregnancy. It may also be used to visualize other gynecological situations in non-pregnant women. It is also used to look for causes of upper abdominal pain which may be related to problems in the liver, gallbladder, pancreas or kidneys. Ultrasound is also used to evaluate the breast, heart, thyroid, testes and veins. Often times ultrasound is used in conjunction with other diagnostic tests.
Ultrasound is like the sonar they use in the ocean. Since your body is largely made up of water, when high frequency sound waves are passed through it, some bounce back and create an image. When a sound wave hits tissue in your body, it bounces back to the transducer (which is the part of the machine that emits and picks up the sound waves). The waves picked up by the transducer are not the same as when they were sent out. By feeding this information into a high-speed computer the waves are used to create a detailed picture.
Depending upon which area of the body to be examined, you may be asked to change into a gown. You will be asked to lie down and a special gel will be placed over the body area to be examined or directly on the transducer, which will come in contact with your skin. You will be asked to remain still. A certified technician will then slowly pass the transducer over the area. An image will appear on a video screen and pictures will be taken of the image for a permanent record. You may be asked to hold your breath or assume a different position. Depending upon the exam, you may be a bit uncomfortable from having a full bladder. Certain gynecological examinations require the insertion of a special transducer into the vagina. This transducer is smaller than the instruments used during a pap smear. The ultrasound exam is usually fast, with minimal discomfort.
Ultrasound is a very safe, simple, non-invasive procedure that utilizes no radiation.
The following tests need no preparations: Breast, Thyroid, Vascular, Testes. For Obstetrical, pelvic and renal examinations, start with an empty bladder. Ninety minutes before the exam drink 48 ounces of water over a 60 minute period. Do not empty your bladder until the exam in complete. For Abdominal examinations, such as for gallbladder, liver and pancreas, do not eat or drink after midnight . Dynamic Medical Imagingtions may be taken with a small amount of water. No smoking the morning of the exam.
You may resume your normal activities.