Ultrasound is just like normal sound except that it is of a higher pitch than the human ear can detect. These high frequency sound waves are passed through the area of the body that is being examined and reflect back at different rates from different densities. Fluid for example has a different reflection rate than muscle tissue. The reflecting sound waves are picked up by the ultrasound machine and entered into a computer which uses the information to construct images.

Ultrasound is an extremely safe and non invasive method of imaging as it does not emit any radiation. As a result it is the method used to assess the development of unborn babies as imaging techniques that involve radiation may harm the foetus.

Ultrasounds are used to detect the structure of internal organs, muscles and tendons and unborn babies. Doppler ultrasounds measure the flow of blood through blood vessels and are usually used to detect narrowing of arteries, blood clots and the direction of blood flow.