Expert reviewer, Dr Daniel Boxer, Consultant Radiologist
Next review due June 2021

An ultrasound is a type of scan that uses sound waves to produce images of the inside of your body. It’s used to detect changes in the look, size or outline of your organs, tissues and vessels, or to detect abnormal masses such as cancer.

An image showing a person having an ultrasound scan

About ultrasound

An ultrasound scanner looks a bit like a home computer system. There’s a hard-drive, keyboard, display screen, and a small hand-held scanner. The hand-held scanner has a transducer that sends out sound waves. A transducer is a device that changes sound to electricity, like a two-way microphone. The sound waves bounce off the organs inside your body and are then picked up again by the transducer. The transducer is linked to a computer that creates real-time images from these reflected sound waves. The images are displayed on the screen. The pictures are constantly updated so the scan can show movement.

A technician called a sonographer may carry out your ultrasound. Sonographers have had special training in taking ultrasound. Alternatively, a radiologist (a doctor who specialises in using imaging methods) may take your ultrasound.

Types of ultrasound

You can have an ultrasound on different parts of your body, and for many different reasons. You might need one to check for problems inside your body or to check the health of your baby when you’re pregnant. An ultrasound is also a helpful tool to guide your doctor during procedures.

An ultrasound of your heart is called an echocardiogram. There’s also a type of ultrasound called a Doppler ultrasound, which can monitor blood flow in your blood vessels. Any change in the pitch or frequency of the sound waves helps to estimate how fast your blood is flowing. This can help detect blood clots or narrowed blood vessels, for example.

A transvaginal ultrasound is a type of ultrasound scan that checks for gynaecological problems and can look at your womb, fallopian tubes or ovaries.

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What happens during an ultrasound?

An ultrasound scan can take anything from five minutes to about half an hour depending on why you’re having it. The person doing your scan will explain what’s involved. You might need to wear a gown. If you’re having a scan of your pelvis or bladder, you may need to drink something before so you have a full bladder.

You’ll usually need to lie on your back on a couch. Your sonographer will put some gel on your skin on the area they’re going to examine. The gel allows the sensor to slide easily over your skin and will help to produce clearer pictures. Your sonographer will hold the sensor firmly against your skin and move it over the surface. They may ask you to take some deep breaths or to move into different positions so they can get the best possible images.

An ultrasound isn’t painful but you might feel some slight discomfort as the sensor is pressed against you, particularly if the area is tender.

If you’re having a transvaginal ultrasound which looks at your womb, fallopian tubes and ovaries, you’ll need to lie on your back and raise your knees. Your sonographer will then put a slim-line lubricated sensor (like the shape of a tampon) into your vagina. They’ll put a protective cover over the sensor. It’s important to tell your hospital if you have a latex allergy so they use a suitable cover.

You can still have a transvaginal scan when you’re on your period. If you don’t wish to have a transvaginal scan, contact the ultrasound department or your doctor to discuss if there are any alternative options. A transvaginal scan isn’t painful, but you might find it uncomfortable.

After an ultrasound, your sonographer will wipe the gel off your skin but if any is left, it won’t stain your clothing. You can usually go home when you feel ready.

How long does it take to get ultrasound results?

Your sonographer may talk you through the results of the ultrasound during or straight after your scan. Or they may arrange for the results to be sent to your doctor who will go through them with you. Ask how long it should take to get the results through if they go to your doctor.

Are there any risks?

An ultrasound is safe because it doesn’t use any radiation. So, unlike scans such as X-rays and CT scans which do use radiation, there aren’t any of the associated risks. Even so, ultrasound scans should only be done for clear medical reasons. You shouldn’t have an ultrasound scan unnecessarily.

What are the alternatives to an ultrasound?

Alternatives to ultrasound depend on what you’re having it for. It will also depend on what part of your body is being looked at, and your individual circumstances. Alternative scans may include:

Your doctor will talk you through which type of scan is most suitable for you.

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Related information

    • Going for an ultrasound scan. British Medical Ultrasound Society., accessed 9 May 2018
    • General ultrasound. Radiological Society of North America., reviewed 9 March 2018
    • Ultrasound scanning – non-obstetric. PatientPlus., last checked 23 December 2015
    • Radiology FAQs. Royal College of Radiologists., accessed 9 May 2018
    • Echocardiography. PatientPlus., last checked 27 November 2015
    • Transvaginal ultrasound. Royal Australian and New Zealand College of Radiologists., last modified 31 August 2017
    • Personal communication, Dr Daniel Boxer, Consultant Radiologist, 14 May 2018
  • Reviewed by Rachael Mayfield-Blake, Freelance Health Editor, June 2018
    Expert reviewer, Dr Daniel Boxer, Consultant Radiologist
    Next review due June 2021

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