An ultrasound scan uses sound waves to build up a picture of internal organs. It can show changes in different organs and helps doctors to know if a lump or abnormal area is cancer or not.
Doctors sometimes use an ultrasound scan when they are doing a biopsy (removing a small piece of tissue). The scan helps to guide them to the exact area.
A small device called an ultrasound probe is used. The probe gives off sound waves that bounce off different parts of the body and make “echoes”. The echoes are converted into a picture by a computer.
The probe is moved over the skin or inserted into an opening in the body, such as the back passage (rectum).
There are three main types of ultrasound scan. The type used will depend on the part of the body being looked at:
For an external ultrasound the probe is moved over the skin. This type of ultrasound helps doctors look at organs and tissues that can be assessed through the skin. These organs include the liver, kidneys, muscles or joints.
Once you are lying comfortably on your back, a doctor or nurse spreads gel on the skin over the area to be scanned. They pass the probe over the area. This test is painless and takes between 15 and 45 minutes.
For an internal ultrasound, the probe is inserted into the body. There are two types:
For a transvaginal ultrasound the probe is inserted into the vagina to look at the ovaries and womb. You will be asked to lie on your back. A doctor or nurse will pass a small, lubricated probe gently into the vagina.
For a transrectal ultrasound the probe is inserted into the back passage (rectum) to look at the prostate and rectum. You will be asked to lie on your left side with your knees bent up. A doctor or nurse will pass a small, lubricated probe gently into the rectum.
Endoscopic ultrasound (EUS)
For an endoscopic ultrasound, the probe is attached to a thin, flexible tube (endoscope). The probe is inserted into the body. It can be used to look at areas, such as the:
- gullet (oesophagus) and stomach
- throat and lungs - an endobronchial ultrasound (EBUS).
You will usually be given a sedative to help you relax. Sometimes you may have a general anaesthetic. You will be asked to lie on your side. The doctor will then pass the endoscope into your mouth and through to the area being looked at.
An endoscopic ultrasound takes about between 15 and 45 minutes. It can be uncomfortable, but should not be painful. It may make you feel sick.
Having an ultrasound
The hospital sends you information about the scan so you know what to expect.
Depending on which part of the body is being scanned, you may be asked:
- not to eat or drink anything for a few hours before the scan
- to drink plenty of water but not go to the toilet until after the scan.
These help to get a clear picture.
You may also be asked to remove your clothing and wear a hospital gown.
After the scan
You will usually be able to go home as soon as the scan is over. If you have had a sedative, you should not drive for 24 hours. Ask a family member or friend to drive you home. If you have had an anaesthetic you may have to stay in hospital for a few hours.
It can take from a few days up to a week to get the results. Waiting for test results can be a worrying time. Talking to your family and friends about how you feel can help. You can also speak to your doctor or nurse if you have any problems, or if you need more support.