What Is Ultrasonography? - Definition, History & Uses

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  • 0:04 What Is Ultrasonography?
  • 0:41 How Does Ultrasonography Work?
  • 1:38 History of Ultrasonography
  • 2:27 Uses of Ultrasonography
  • 3:35 Lesson Summary
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Lesson Transcript
Instructor: Bethany Lieberman

Bethany is a certified OB/GYN nurse who has a master's degree in Nursing Education.

Ultrasonography is a diagnostic medical procedure that uses sound waves to produce images on a screen, which allows medical providers to view internal structures of the body. In this lesson, you'll learn more about ultrasonography and its uses.

What Is Ultrasonography?

Patty is pregnant with her first child. Her doctor put in a referral for an ultrasound, but Patty has never had an ultrasound before and has some concerns. She wants to know what the procedure is and whether it's safe for her unborn baby.

Patty's doctor explains that ultrasonography is a relatively safe diagnostic medical procedure where sound waves are introduced into the body using a transducer. The sound waves bounce off the bones and tissues in the body and produce a black and white image on a monitor. The procedure is safe because it does not use ionizing radiation like an x-ray or CAT scan, which should be avoided in pregnancy.

How Does Ultrasonography Work?

The ultrasound image is produced by sending sound waves of 1-10 million hertz through a transducer by placing it over structures of the body. The sound waves are either absorbed or bounce back to crystals in the head of the transducer. For example, sound waves go through areas that are hollow or fluid-filled, such as the bladder and blood vessels. These areas appear black on the screen. Areas filled with tissue allow some penetration and refraction of sound and produce a grayish-white image. Really hard structures,such as bone, produce a bright white image as the sound waves completely bounce back to the transducer.

In pregnancy, this allows providers to have an image of the woman's womb. The amniotic fluid will appear black, which enhances the bones and tissues of the baby, which will appear white. The doctor explains to Patty that the ultrasound is ordered so he can assess how well the baby is developing, determine the gender of the baby, and detect any abnormalities. He can also measure Patty's cervix and ovaries.

History of Ultrasonography

We can thank the French for the invention of ultrasound. Physicist Pierre Curie first used ultrasound in 1877. Imaging was discovered by Paul Langevin 35 years later. Ultrasound was first used during wartime to detect submarines and wreckage in the ocean. It was used medically in the 1920s for physical therapy for Europe's soccer teams. Austrian physician Karl Dussik and his brother Friedrich Dussik were the first to use ultrasound for diagnostic purposes, such as looking at brain structures, in the 1940s.

Real-time ultrasound, similar to the one Patty will have, wasn't developed until the 1980s. This is when actual images could be seen and interpreted. The 90s led to 3D and 4D imaging where the public was able to be viewed and it was possible to recognize familiar images such as facial features of a baby.

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