Ultrasound scans - an overview

Sometimes known as a sonograph, an ultrasound scan is the technique of looking inside the body at soft tissues and liquids via sound waves. No radiation, x-ray, or harmful material is used. Ultrasound or ‘sonar’ images are obtained using high-frequency sound released at around ten million cycles per second (10MHz) which cannot be heard by human beings.

This article provides an overview of ultrasound scans, and is written by Jackie Griffiths, a freelance journalist who writes health, medical, biological, and pharmaceutical articles for national and international journals, newsletters and web sites.

How does the scan work?

A small, hand-held probe or sensor delivers a pulse of ultrasound waves towards the part of the body where the sonographer needs to look. The sensor is attached to a computer via a lead, which translates bounced-back sound waves into pictures on a screen. All this happens very fast, with each pulse of sound lasting about 1/1000th of a second and the returned echoes within another 1/1000th of a second. As the sensor passes over the surface of the skin it sends these pulses of high-frequency sound down inside the body, receiving echoes from the organs and soft tissues. The echoes come back to the sensor in different strengths depending on the density of the object.

An ultrasound scan is completely painless and even the gel used to spread on the skin is often heated these days! An ultrasound scan is often used during pregnancy to see inside the womb and check on baby’s progress.

Why do you need it?

Apart from during pregnancy to monitor an unborn baby, an ultrasound scan is also used to:

  • Obtain pictures of your internal organs
  • Discover any internal swelling or abnormalities
  • Assist doctors with a diagnosis
  • Assess the effects of treatment
  • Detect blood flow and blockages
  • Assist doctors during surgical procedures
  • Treat aching joints and muscles

What happens during the scan?

You will be taken into a room, often with dimmed lighting so that the sonographer can see the screen in optimum light, and asked to lie down on a bed or examination table. You may be asked to undress beforehand and put on a gown. The area of the skin directly over the part of the body that needs to be examined will be moistened with a special lubricant gel or oily fluid. The rounded head of the ultrasound sensor is then passed slowly across the relevant part of the skin, but you will not feel or hear anything. The sonographer will then be able to look at and assess live pictures of your internal organs instantly on the screen. After ten or fifteen minutes, your skin will be wiped dry and you will be able to get up immediately.

Prior preparations needed

Quite often there is no preparation required before having an ultrasound scan, but occasionally you will be asked either to make sure you have a full bladder, or an empty one! Follow the instructions you have been given so the sonographer will have the best views of the area to be examined. Different parts of the body may require different volumes of bladder fullness.

What are the risks?

Ultrasound scans are thought to be completely safe, and there are no known risks associated with the procedure.

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