Ultrasound is a scanning technique that uses ultrasound waves to produce an image. Ultrasound does not use ionising radiation, so is generally considered safer than those types of scan which do, therefore it is often used as a first line investigation.
For an ultrasound scan, the patient will usually lie on a bed, while the sonographer or doctor puts a small amount of clear gel over the area that is being investigated. A small handheld probe is then passed over the skin at varying pressures and the resultant images are viewed on a screen attached to the ultrasound machine. Ultrasound scans are quick and generally pain-free.