An ultrasound scan is a picture of part of the inside of the body using sound waves of a frequency above the audible range of the human ear. A small device called an ultrasound probe is used, which gives off high-frequency sound waves.
You can’t hear these sound waves, but when they bounce off different parts of the body, they create “echoes” that are picked up by the probe and turned into a moving image.
This image is displayed on a monitor while the scan is carried out.
Who will perform the ultrasound scan?
The examination may be performed by a trained doctor or a sonographer. Sonographers are radiographers who have trained further to specialise in the technique of ultrasound scanning. They carry out a great number of these examinations and may also provide a descriptive report of their findings to your doctor.
Preparing for an ultrasound scan
Before having some types of ultrasound scan, you may be asked to follow certain instructions to help improve the quality of the images produced. For example, you may be advised to:
- drink water and not go to the toilet until after the scan – this may be needed before a scan of your unborn baby or your pelvic area
- avoid eating for several hours before the scan – this may be needed before a scan of your digestive system, including the liver and gallbladder
- iIn some cases, you may also be given an injection of a harmless substance called a contrast agent before the scan, as this can make the images clearer.
Depending on the area of your body being examined, the hospital may ask you to remove some clothing and wear a hospital gown.
During the scan
You will be taken into a room where you will be asked to lie down on a couch; the room may be dimmed so that the pictures on the screen can be seen more clearly. A gel will be applied to your skin over the area to be scanned, for example, the abdomen. The gel allows the sensor to slide easily over the skin and helps to produce clearer pictures.
The doctor/sonographer will slowly move the sensor over your skin while viewing the images on the screen. Records of selected images will be made so that they can be viewed later. Upon completion, the gel will be wiped off and you will be free to get dressed.
How long will it take?
The process of carrying out a scan usually takes about 15–30 minutes
Are there any risks?
No, there are no known risks and it is considered to be very safe.
The scan will be examined after your visit and a written report on the findings sent to your GP or consultant