Your Ultrasound Examination: a guide for patients
Your doctor has recommended that you have an ultrasound examination to find out more about your problem. This leaflet will tell you what to expect.
What is an ultrasound examination?
An ultrasound examination takes a picture of the inside of your body. However, it is not the same as an X-ray, because it does not involve radiation.
Ultrasound works by transmitting high frequency sound waves through your skin (you won’t feel or hear anything) which ‘bounce’ off your body’s internal organs. The patterns of the sound waves’ movements show up as a picture on a screen, on which the doctors can see and diagnose problems. Having an ultrasound examination is painless and very safe - the technique is even used on babies.
What is ultrasound used for?
The ultrasound technique is used to examine many different organs such as your liver and kidneys, the heart, the pelvis, and major blood vessels. It can also be used to examine the eyes, the breasts, and the thyroid gland.
During pregnancy, ultrasound can be used to take a picture of the unborn baby and to check that it is healthy. Ultrasound waves can’t pass through bone (so you couldn’t use it to examine someone’s brain, as their skull would block the waves) or through air (so it’s not used for examining lungs).
How can I prepare for my ultrasound examination?
You don’t generally need to do anything special before you have an ultrasound. However, if certain parts of your body are being investigated you may be asked to alter your diet slightly to help your picture come out better. Here are some common examples:
· If you are having your pelvic area examined by ultrasound, it will be easier to see your insides if you have a full bladder, so you might be asked to drink a few large glasses of fluid (1 - 1½ pints) 45 minutes before the examination.
· If your gall bladder or pancreas are being examined, you might have to avoid eating for 4-6 hours before the test and drink only clear fluids (e.g. water), because if there is something in your stomach this could block the view of your other organs.
· If your liver or kidneys are being looked at, you may be asked to avoid fizzy drinks and wind-producing foods like beans for up to 48 hours before your ultrasound. This is because the ultrasound waves can’t pass through air, so it is helpful if you have as little gas in your digestive system as possible when you are being examined.
What will happen during my ultrasound examination?
You will lie on a couch in a slightly darkened room, with a screen beside the couch to show the ultrasound picture. One person will operate the ultrasound equipment, but there may be other medical staff in the room.
To help the sound waves pass through your skin, clear oil or gel will be put on your skin over the area that is being examined. It will wipe off easily afterwards, but please don’t wear any clothes that could be damaged by stains.
The ultrasound operator will slide a small hand-held instrument like a blunt ended pen over your skin, which will transmit the sound waves. It won’t hurt, although if the area is already tender you might feel a bit uncomfortable if the operator has to press firmly to get a clear image. The picture of your insides will appear on the screen and the operator will examine these. You might be asked to change position so that the area being examined can be seen from different angles. The examination will take between 10 and 45 minutes.
What will happen after the examination?
You will probably be able to go straight home. If no other tests are needed, you can eat, drink and go back to your usual routine right away. The doctor who decided you should have the ultrasound will be sent the results of your examination, and he will discuss these with you.
We hope this leaflet has answered your questions. Please ask your doctor or the ultrasound operator if there is anything you feel worried or unsure about.