What It Is
An ultrasound is an imaging test that uses high-frequency sound waves, rather than radiation, to create real-time images of structures inside the body.
What It Checks
Ultrasound can be used to examine a wide range of soft tissue structures, including organs in the abdomen, blood vessels, and, in the case of pregnancy, a developing fetus. Because it produces images in real time, it's also well suited to observing movement, such as blood flow or the beating of the heart.
Why It's Used
Ultrasound is commonly used to examine internal organs, evaluate blood flow through vessels, and monitor pregnancy, valued in particular for not involving radiation and for being able to provide immediate, real-time images during the examination itself.
How It's Done
During an ultrasound, a device called a transducer is placed against the skin, usually after applying a small amount of gel to help it make good contact. The transducer sends out sound waves and detects the echoes that bounce back from internal structures, which a computer then converts into a visual image displayed on a screen in real time.
Background
The use of sound waves for imaging drew on sonar technology developed for detecting objects underwater, principles that researchers began adapting for medical use in the mid-20th century. Early medical ultrasound machines were large and produced relatively simple images, but the technology advanced considerably over subsequent decades, eventually enabling detailed, real-time imaging. Ultrasound has since become one of the most widely used imaging tools in medicine, valued for its safety profile and versatility across many different types of examinations.