Ultrasound scan

An ultrasound scan uses high-frequency sound waves to produce live images of the inside of your body, such as your muscles, organs or a baby in the womb [1]. A small handheld device called a probe sends out sound waves and picks up the echoes that bounce back [1].

Ultrasound is used to investigate symptoms such as pain, swelling or a lump, to monitor an existing condition, to check a baby during pregnancy, and to guide surgeons during certain procedures such as taking a biopsy [1].

The hospital will give you instructions depending on the area being scanned [1]. For some scans you may be asked to drink water beforehand so your bladder is full, or to avoid eating for a few hours; for others you may need to remove jewellery or clothing from the area [1].

Most scans are external: a gel is put on your skin and the probe is moved over the area, usually taking between 10 and 45 minutes [1]. An internal scan uses a smaller probe gently passed into the vagina or back passage, and you can ask for it to stop at any time [1]. An endoscopic scan passes a probe on the end of a thin tube down your food pipe for a closer look at areas such as the stomach [1].

Sometimes the person carrying out the scan can tell you the results straight away, but often the images need to be looked at and a report sent to the doctor who referred you, which can take several weeks [1]. You may need a follow-up appointment to discuss what was found [1].

Ultrasound scans are considered very safe. Unlike X-rays and CT scans, they do not use any radiation, and there are no known risks from the sound waves used [1].