How Does the Procedure Work?

Ultrasound imaging is based on the same principles involved in the sonar used by bats and ships. When a sound wave strikes an object, it bounces back and creates an echo. By measuring these echo waves, it is possible to determine the distance of the object and the object’s size, shape, and consistency (whether the object is solid or filled with fluid).

In medicine, ultrasound is used to detect changes in appearance, size, or contour of organs, tissues, and vessels or to detect abnormal masses, such as tumors.

In an ultrasound examination, a transducer sends the sound waves into the body and receives the echoing waves. When the transducer presses against the skin, it directs small pulses of inaudible, high-frequency sound waves into the body. As the sound waves bounce off internal organs, fluids, and tissues, the sensitive receiver in the transducer records tiny changes in the sound’s pitch and direction. These signature waves are instantly measured and displayed by a computer, which creates a real-time picture on the monitor. One or more frames of the moving pictures are typically captured as still images. Short video loops of the images may also be saved.

Doppler ultrasound, a unique application of ultrasound, measures the direction and speed of blood cells as they move through vessels. The movement of blood cells causes a change in the pitch of the reflected sound waves (called the Doppler effect). A computer collects and processes the sounds and creates graphs or color pictures, representing blood flow through the blood vessels.

How Is the Procedure Performed?

For most ultrasound exams, you will be positioned lying face-up on an examination table that can be tilted or moved. Patients may be turned to either side to improve the quality of the images.

A clear water-based gel is applied to the area of the body being studied to help the transducer make secure contact with the body and eliminate air pockets between the transducer and the skin that can block the sound waves from passing into your body. The sonographer (ultrasound technologist) or radiologist then places the transducer on the skin in various locations, sweeping over the area of interest or angling the sound beam from a different location to better see an area of concern.

Doppler sonography is performed using the same transducer.

The ultrasound images will then be reviewed, with the whole examination is usually being completed within 30 minutes to an hour. Occasionally, complex examinations may take longer.

What Will I Experience During and After the Procedure?

Ultrasound examinations are painless and easily tolerated by most patients.

After you are positioned on the exam table, the radiologist or sonographer will apply the warm, water-based gel to your skin and place the transducer firmly against your body, moving it back and forth over the area of interest until the desired images are captured. There is usually no discomfort from pressure as the transducer is pressed against the area.

If scanning is performed over an area of tenderness, you may feel pressure or minor pain from the transducer.

If a Doppler ultrasound study is performed, you may hear pulse-like sounds that change in pitch as the blood flow is monitored and measured.

Once the imaging is complete, we will wipe the ultrasound gel off your skin. Any portions that are not wiped off will dry quickly. The ultrasound gel does not usually stain or discolor clothing.

After an ultrasound examination, you should be able to resume your normal activities immediately.