Ultrasound waves are high frequency sound waves that cannot be heard by the human ear. These waves are used to create live images of the inner structures of the body including the hard and soft tissues. These images, also called sonograms, are used for diagnosis of various conditions and may be used to guide certain interventional procedures.
How ultrasound works
The sonographer or technician who performs the ultrasound uses a hand-held device called a transducer which produces the ultrasound waves. The waves pass through the body and reflect off the different internal structures and are picked up again by the transducer which relays this information to a computer. The way in which the waves reflect are processed to determine the shape, size and consistency of the tissues and organs and to create live images on a computer screen. Modern day ultrasound has the capability of producing 3D or 4D moving images.
Ultrasound imaging is used during pregnancy to evaluate the growing fetus. It can help determine the date of delivery and identify any abnormalities. Ultrasound may be used to evaluate organs and soft tissues and to determine how blood is flowing within the vessels. It can also help diagnose a variety of medical conditions.
Some types of ultrasounds are performed using transducers that are inserted into the body's openings such as the vagina, rectum or esophagus to obtain a clear picture of specific tissue or organs. Certain procedures such as a biopsy, obtaining a sample of tissue from within the body, may be guided by ultrasound. Ultrasound waves at certain frequencies also are known to have therapeutic benefits.
Before undergoing ultrasound you may be instructed to fast or drink several glasses of water to ensure a full bladder. This helps create better images depending on what is being tested.
A gel which helps conduct sound waves and provides lubrication is first applied to the skin over the area being tested. The transducer is then gently glided over the gelled area as ultrasound waves are passed through the body. The examiner observes the screen, interprets the images and notes findings. You remain awake throughout the procedure and may discuss the findings with the examiner. The entire procedure takes about 30 minutes to an hour. You may return to your regular activities once the procedure is complete.
Advantages & Disadvantages
Ultrasound waves, unlike radiation, have no harmful effects and are completely safe for fetal examinations. Another advantage of ultrasound includes the ability to view soft tissue which is not clear on X-rays. Also, ultrasound equipment is portable allowing the procedure to be performed at the patient's bedside.
A disadvantage of ultrasound is that bones or areas with gas or air, such as the bowels or lungs, are not well visualized as ultrasound waves do not transmit well through these structures.
Risks and complications
There are no known identified risks with the use of ultrasound.