Ultrasound uses high-frequency, inaudible sound waves to demonstrate the internal organs and systems of body by creating their images. The images are produced when the sound waves are directed into the body then reflected back to a scanner that measures them.

How does an ultrasound work?

Ultrasound travels freely through fluid and soft tissues. However, ultrasound is reflected back when it hits a more solid (dense) surface. For example, the ultrasound will travel freely through blood in a heart chamber. But, when it hits a solid valve, a lot of the ultrasound reflects back to generate black and white images.

How is an ultrasound scan performed?

The way the ultrasound scan is performed depends on the purpose of the examination. The scanner can be used externally on the skin, or through the natural openings of the body, such as the vagina. For example, if the kidneys or liver are being examined the patient will be told to lie on their back or side on an examination table. Some special gel is spread over the skin, enabling the scan to define the organs as clearly as possible.

What is an ultrasound test used for?

It is used in many situations. The way the ultrasound bounces back from different tissues can help to determine the size, shape and consistency of organs, structures and abnormalities. So, it can:

  • Help to monitor an unborn baby’s development, and check for abnormalities, if any.
  • Detect abnormalities of heart structures such as the heart valves. (An ultrasound scan of the heart is called an echocardiogram).
  • Help to diagnose problems of the liver, gallbladder (such as gallstones), pancreas, thyroid gland, lymph nodes, ovaries, testes, kidneys, bladder and breast. For example, it can help to determine if an abnormal lump in one of these organs is a solid tumor or a fluid-filled cyst.
  • Detect abnormal widening of blood vessels (aneurysms).

What types of ultrasound are there?

There are basically seven different ultrasound scans; however the principle process is the same. The different types of procedures include:

Transvaginal Scans: Specially designed probe transducers are placed inside the vagina to generate sonogram images. These scans are used during the early stages of pregnancy.

Standard Ultrasound: Traditional ultrasound scan which uses a transducer over the abdomen to generate 2-D images of the developing fetus.

Advanced Ultrasound: This scan is similar to the standard ultrasound, but the exam targets a suspected problem and uses more sophisticated equipment.

Doppler Ultrasound: This imaging procedure measures slight changes in the frequency of the ultrasound waves as they bounce off moving objects, such as blood cells.

3-D Ultrasound: Uses specially designed probes and software to generate 3-D images of the developing fetus.

4-D or Dynamic 3-D Ultrasound: Uses specially designed scanners to look at the face and movements of the baby prior to delivery.

Fetal Echocardiography: Uses ultrasound waves to assess the baby’s heart anatomy and function. This is used to help assess suspected congenital heart defects.