Ultrasound

An ultrasound is a type of scan that uses sound waves to create images of the inside of your body. It can pick up changes in your organs, tissues, blood vessels, and joints. This may help to diagnose some health problems. Ultrasound scans are also used in certain procedures and during pregnancy.

About ultrasound

An ultrasound machine consists of a small hand-held scanner (‘probe’). The probe contains a transducer that sends out sound waves. The sound waves are a high frequency that you can’t hear. They bounce off the organs and tissues inside your body and are picked up again by the probe. A layer of water-based gel is placed on your skin under the probe. This helps with the transmission of the sound waves.

The probe is linked to a computer that creates real-time images from the reflected sound waves. The images are displayed on a monitor in various shades of grey. The pictures are constantly updated. This means the scan can show movement. The pictures can be captured, saved, and shared with you.

Hand-held ultrasound machines are much smaller and easier to transport than the computer-based versions. Several different types of healthcare professional may carry out ultrasound scans. These include sonographers (specialists in ultrasound) and radiologists (doctors specialising in imaging methods).

Ultrasound uses

You can have an ultrasound on different parts of your body. These include your:

• muscles and joints – to check for an injury or health conditions such as osteoarthritis 
• tummy (abdomen) – to check the health of organs such as your liver, gallbladder, kidneys, and pancreas
• reproductive organs such as your womb and ovaries, or prostate and testes
• breasts – to check lumps, alongside other tests such as mammograms and biopsies
• lumps under your skin, anywhere around your body
• blood vessels – to check for conditions such as deep vein thrombosis, varicose veins, or abdominal aortic aneurysm, or to assess your risk of stroke 

You may also have an ultrasound to:

• help diagnose cancer
• check the health of your baby when you’re pregnant
• monitor infertility treatments 

Ultrasound is also used to help doctors and surgeons perform certain procedures. It helps your doctor to guide the needle to the right place. These procedures include:

• biopsy, which involves taking a sample of cells using a small needle
• steroid joint injections

The healthcare professional referring you will explain why they’re recommending you have an ultrasound scan. If you have any questions, make sure you ask them. You’ll need to give your consent when you go for the scan.

Types of ultrasound

There are three main types of ultrasounds: external, internal, and endoscopic.

External ultrasound

The ultrasound practitioner moves the ultrasound probe over your skin.

Internal ultrasound

The ultrasound practitioner places the probe inside your body to take the scan. This may be:

• a transvaginal ultrasound in your vagina to check your womb and ovaries
• a transrectal ultrasound in your back passage to check your prostate, if you have one, or to take images inside your back passage

Endoscopic ultrasound

This is a combination of an endoscopy (gastroscopy) and an ultrasound scan. The practitioner uses a probe attached to a long, thin, flexible tube (an endoscope) to look further inside your body. The probe is passed into your mouth and down your food pipe (oesophagus) to check for problems in your digestive system.

Special types of ultrasounds

Some types of ultrasounds use special techniques. These include the following.

• Echocardiogram. This is an ultrasound of your heart. An echocardiogram can create real-time images of blood flowing through your heart.
• Doppler (or Duplex) ultrasound. This can monitor the blood flow in your blood vessels. It can show how fast and in which direction your blood is flowing. This can help to detect blood clots or narrowed blood vessels.
• 3D ultrasound. Standard ultrasound creates 2D (flat) images. But newer technology is also able to create 3D ultrasound images. This may make it easier to see any problems.
• Elastography. This can measure the stiffness of organs inside your body. It’s most commonly used to check if you have liver fibrosis (scarring). Fibrosis can be due to alcohol-related liver disease, non-alcoholic fatty liver disease, and hepatitis.
• Contrast-enhanced ultrasound. This uses contrast agent (dye) to show up your vessels or organs more clearly. Your doctor or sonographer injects very small gas bubbles with the contrast agent into your vein before the procedure.

Preparation for ultrasound

Whether or not you need to do anything to prepare for your ultrasound depends on the type of ultrasound you’re going to have. For some scans, you may need to remove some clothing. So, it’s usually helpful to wear loose-fitting clothes that you can take off easily.

For some types of ultrasounds, you may be asked to follow specific instructions about eating or drinking before your procedure. This is to make it easier for the practitioner to create clear images.

If you’re having a scan of your womb, bladder, or kidneys, you may need to drink something before your appointment, so you have a full bladder. Sometimes you may then be asked to go for a pee, so the ultrasound can be repeated when you have an empty bladder.

If you’re having a scan of your gallbladder or pancreas, you may be asked to stop eating for about six hours before the scan.

If you’re having a transrectal ultrasound, you may be asked to make sure your bowel is empty before your appointment.

If you’re having an endoscopic ultrasound, you’ll usually need to stop eating at least six hours beforehand, so your bowel is clear. You can usually carry on drinking for two hours before the test. You may need to have more preparation as part of having a gastroscopy.

Ultrasound procedure

An ultrasound appointment can take anything from 10 minutes to 30 minutes. This will depend on why you’re having it. The person doing your scan will explain the procedure to you and check you’re happy to go ahead. You may be asked to remove clothing or change into a hospital gown. This depends on which part of your body is being scanned.

If you’re having an abdominal ultrasound, you’ll usually need to lie on your back on a couch. Your ultrasound practitioner will put some gel on your skin on the area they’re going to scan. This may feel cold. The gel helps to transmit the soundwaves between your body and the probe.

The practitioner will hold the probe 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 may feel some slight discomfort when the probe is pressed against you, particularly if the area is tender. Tell the person doing your scan if you feel uncomfortable.

After an ultrasound, your practitioner will usually wipe the gel off your skin. If any is left, it won’t stain your clothing. You’ll be able to wash it off with soap and water when you get home.

Transvaginal ultrasound

If you’re having a transvaginal ultrasound, the ultrasound practitioner will ask you to lie on your back with your knees raised and legs apart. If this is difficult for you, you may be able to lie on your side with your knees pulled up to your chest instead.

The practitioner inserts a small, thin ultrasound probe (similar in size to a tampon) into your vagina. They’ll put a protective cover over the probe. It will have some gel on it. It’s important to tell your hospital if you have a latex allergy so they can use a suitable cover.

The test may be a bit uncomfortable, but it shouldn’t be painful.

Transrectal ultrasound

If you’re having a transrectal ultrasound, your practitioner will ask you to lie on your left side with your knees pulled up towards your chest. Your practitioner will insert a small, thin ultrasound probe into your back passage. The probe will have a protective cover and lubricating gel on it. If you have a latex allergy, tell the practitioner so they can use a suitable cover.

A transrectal ultrasound may feel a bit uncomfortable but it shouldn't be painful.

Endoscopic ultrasound

You’ll usually have a sedative for an endoscopic ultrasound. This will make you feel relaxed and sleepy, but you’ll still be awake.

The healthcare professional performing the test may spray some local anaesthetic on your throat to numb it. They’ll then pass the endoscope through your mouth and guide it towards the area of your body that’s being scanned. You may need to swallow as the tube goes down. Once the practitioner has taken the images they need, they’ll gently remove the endoscope.

Aftercare for ultrasound

After an ultrasound, you can usually go straight home or continue with your usual activities. If you’ve had a sedative, you may need to rest for a while until the effects have worn off. Ask a friend or family member to take you home by car or taxi – ideally not public transport. The effects of sedation can last up to 24 hours, so ask them to stay overnight to look after you. Don’t drive, drink alcohol, operate machinery, or make any important decisions during this time. Your hospital will give you more information about having a sedative before your scan.

During an endoscopic ultrasound, your doctor may have used a spray to numb your throat. It’s best to wait about an hour for this to wear off before you eat or drink anything. You might have a sore throat for a few days afterwards.

Getting your ultrasound results

Ultrasound scan results will usually be sent to the healthcare professional who referred you for the scan. They will then discuss the results with you. Ask them how long it should take to get the results.

Risks of ultrasound

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

Alternatives to ultrasound

Alternatives to ultrasound imaging depend on why you’re having the scan. It will also depend on which part of your body is being looked at and your individual circumstances. Alternative scans may include:

• a CT scan
• an MRI scan
• X-rays

You may have ultrasound as well as these other scans. Your doctor will talk you through which type of scan is most suitable for you.