In ultrasound, a beam of sound at a very high frequency (that cannot be heard) is sent into the body from a small vibrating crystal in a hand-held scanner head. When the beam meets a surface between tissues of different density, echoes of the sound beam are sent back into the scanner head. The time between sending the sound and receiving the echo back is fed into a computer, which in turn creates an image that is projected on a television screen. Ultrasound is a very safe type of imaging; this is why it is so widely used during pregnancy. Doppler ultrasound A Doppler study is a noninvasive test that can be used to evaluate blood flow by bouncing high-frequency sound waves (ultrasound) off red blood cells. The Doppler Effect is a change in the frequency of sound waves caused by moving objects. A Doppler study can estimate how fast blood flows by measuring the rate of change in its pitch (frequency). A Doppler study can help diagnose bloody clots, heart and leg valve problems and blocked or narrowed arteries. What to expect? After lying down, the area to be examined will be exposed. Generally a contact gel will be used between the scanner head and skin. The scanner head is then pressed against your skin and moved around and over the area to be examined. At the same time the internal images will appear onto a screen.

Ultrasound imaging, also called ultrasound scanning, is a method of obtaining pictures from inside the human body through the use of high frequency sound waves. Obstetric ultrasound refers to the specialised use of this technique to produce a picture of your unborn baby while it is inside your uterus (womb). The sound waves are emitted from a hand-held nozzle, which is placed on your stomach, and reflection of these sound waves is displayed as a picture of the moving foetus (unborn baby) on a monitor screen. No x-rays are involved in ultrasound imaging. Measurements of the image of the foetus help in the assessment of its size and growth as well as confirming the due date of delivery.

An X-ray is a high frequency, high energy wave form. It cannot be seen with the naked eye, but can be picked up on photographic film. Although you may think of an X-ray as a picture of bones, a trained observer can also see air spaces, like the lungs (which look black) and fluid (which looks white, but not as white as bones). What to expect? You will have all metal objects removed from your body. You will be asked to remain still in a specific position and hold your breath on command. There are staff present, but they will not necessarily remain in the room, but will speak with you via an intercom system and will be viewing the procedure constantly through a windowed control room. The examination time will vary depending on the type of procedure required, but as a rule it will take around 30 minutes.