An ultrasound scan does not use X-rays and is entirely safe. The ultrasound waves are delivered by a small handheld transducer similar to a microphone. The transducer is moved over the surface of the skin and it picks up the sound waves as they return from various organs within the body. A computer, which is linked to the transducer, turns the sound waves into pictures that are viewed on a monitor. Images are stored and then interpreted by trained specialists.
Ultrasound scans can be used to help doctors to make a diagnosis or assess the effects of treatment. Your doctor will recommend an ultrasound scan based on the type of cancer you have and the information needed. Ultrasound can also be used to detect blood flow and whether there is any narrowing or blockage of blood vessels.
There are no known risks with ultrasound and it is considered to be very safe. The scan does not hurt but you will feel a gentle pressure of the sensor over the skin. If you are to have an internal scan any sensations you may feel will be explained to you. Most scans take about half an hour.
Types of ultrasound scan
There are several types of ultrasound scans. You will be told if you need any special preparation before your scan. All instructions will be on your appointment letter so please read it carefully. Sometimes, doctors need to put a special ultrasound transducer inside the body to get a clearer picture. Special transducers have been developed to 'look inside' the body. You may be asked to arrive with a full bladder or you may be asked to have a fat-free diet .Your appointment letter will tell you if there is any preparation required.
Guided biopsy/fine needle aspirate (FNA)
Other procedures, such as biopsies, may be performed at the same time as the ultrasound. If the sonographer or doctor performing the scan notices an area which looks unusual, in the breast or liver for example, they may want to take a biopsy or fine needle aspirate (FNA) – a sample of cells or tissue – from that area. With some biopsies, for example a liver biopsy, you may need to stay in hospital overnight. You will be warned in advance if this is the case.
Contrast enhanced ultrasound
Your sonographer or doctor may wish to characterise a lesion further by injecting fluid (ultrasound contrast) which is often given into a vein in your arm or hand. The fluid is not radioactive. You will be asked about allergies, tablets and heart conditions to assess your suitability to have the injection.
During your ultrasound scan
An ultrasound scan does not hurt. You only feel gentle pressure of the sensor over your skin. If you are to have an internal scan any sensations you may feel will be explained to you.
Your scan will be carried out by a sonographer, a specialist radiographer, or you may also see a specialist doctor called a radiologist. When you arrive in the department you may be asked to undress and change into a hospital gown. You will then be asked to lie on an examination couch. The lights in the room will be dimmed so that the pictures on the monitor can be seen more clearly.
A gel will be applied to your skin in the area to be scanned, such as the abdomen. The gel allows the sound waves to pass into the body and the transducer to move over the skin more easily. The gel will be wiped off at the end of the scan.
After your ultrasound scan
As soon as the scan is complete you may get ready to go home or back to your hospital ward. The gel will be removed before you get dressed. You may go to the toilet and eat and drink as usual.
There are no side effects to the ultrasound scan and it is safe to drive or return to work after your scan.
Although the person carrying out your scan can see your organs or parts of your body on the screen, an expert must carefully interpret the pictures. He or she will prepare a report and send it to your doctor a few days later.