Ultrasound scans

An ultrasound uses sound waves to build up a picture of your internal tissues. Ultrasounds are often used to monitor pregnancies, but they can be used to create pictures of other parts of your body too. The soundwaves are turned into a picture on a computer monitor. 

Before the test

Usually no special preparations are needed. You may be asked to fast (not eat) for a few hours before the test.

• Scan of tummy / pelvic area: You may have to drink a lot of water, as a full bladder can help the doctor to get a clearer picture.
• For a rectal ultrasound to examine your prostate or anus: You may be given some medicine to make sure your bowels are clear before the scan or you may need an enema.

During the scan

Most ultrasounds take place in a hospital radiology department and are performed either by a doctor, radiographer or a sonographer.

There are different kinds of ultrasound scans, depending on which part of the body is being scanned and why.

The 3 main types are:

• External ultrasound scan – the probe is moved over the skin
• Internal ultrasound scan – the probe is inserted into the body
• Endoscopic ultrasound scan – the probe is attached to a long, thin, flexible tube (an endoscope) and passed further into the body.

For an external scan, a lubricating gel is put on your skin to allow the probe to move smoothly. This also ensures there's continuous contact between the probe and the skin/tissue. A gel will be spread over your skin, over the area the doctors are checking. A small device like a microphone is moved back and forth over your skin to take the scan.

Does it hurt?

It might be a little bit uncomfortable if the sonographer (person doing the test) presses the probe against a particular part of your body. Let them know if you’re feeling any discomfort.  

How long does it take?

Most ultrasound scans last between 15 and 45 minutes.

After an ultrasound

Usually there are no after-effects, and you can go home soon after the scan.

You can drive, eat, drink, and return to your other normal activities straightaway if no medication was given.

If you had an endoscopic ultrasound and had a sedative to help you relax, you will usually be advised to stay in hospital for a few hours until the medication starts to wear off.

You will need to arrange for someone to pick you up from the hospital and stay with you for the next 24 hours. You should not drive, drink alcohol, or operate machinery during this time.

You may be told the results of your scan soon after it's been carried out, but in most cases the images will need to be analysed and a report will be sent to the doctor who referred you for the scan.

They will discuss the results with you at your next appointment.