How Does Ultrasound Work?


Quick Answer

An ultrasound machine works by transmitting high-frequency soundwaves into the body and detecting waves that get reflected back to the probe after the sound hits dense tissue, according to Craig Freudenrich, Ph.D., of HowStuffWorks. After the probe, called a transducer, receives the reflected soundwaves, two-dimensional or three-dimensional images display on a screen that depicts the machine's calculations.

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Full Answer

Freudenrich explains the ultrasound machine determines how far away the objects in the image appear due to the speed the soundwaves return to the transducer. These waves normally take a few millionths of a second to travel from the transducer, into the body and back. Ultrasounds detect waves that travel between tissue boundaries, reflect off bone and reach deeper into the body.

The Society of Obstetricians and Gynaecologists of Canada indicates ultrasound devices do not use radiation, unlike x-rays. The imaging technology has been used safely on pregnant women for more than 30 years. Ultrasound determines the size of the baby in the uterus, how the baby's heart functions and the growth patterns of other vital organs.

Doctors use ultrasound technology to evaluate pain, swelling and infection. Organs examined by soundwaves include the heart, liver, gallbladder, spleen, pancreas, kidneys, bladder, uterus, eyes and thyroid. The Radiological Society of North America reveals that a Doppler ultrasound even detects blood flow through major arteries.

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