What is an ultrasound?
An ultrasound is an imaging test that uses sound waves to create a picture (also known as a sonogram) of organs, tissues, and other structures inside the body. Unlike x-rays, ultrasounds don’t use any radiation. An ultrasound can also show parts of the body in motion, such as a heart beating or blood flowing through blood vessels.
There are two main categories of ultrasounds: pregnancy ultrasound and diagnostic ultrasound.
- Pregnancy ultrasound is used to look at an unborn baby. The test can provide information about a baby’s growth, development, and overall health.
- Diagnostic ultrasound is used to view and provide information about other internal parts of the body. These include the heart, blood vessels, liver, bladder, kidneys, and female reproductive organs.
Other names: sonogram, ultrasonography, pregnancy sonography, fetal ultrasound, obstetric ultrasound, diagnostic medical sonography, diagnostic medical ultrasound
What is it used for?
An ultrasound can be used in different ways, depending on the type of ultrasound and which part of the body is being checked.
A pregnancy ultrasound is done to get information about the health of an unborn baby. It may be used to:
- Confirm that you are pregnant.
- Check the size and position of the unborn baby.
- Check to see you are pregnant with more than one baby.
- Estimate how long you have been pregnant. This is known as gestational age.
- Check for signs of Down syndrome, which include thickening in the back of the baby’s neck.
- Check for birth defects in the brain, spinal cord, heart, or other parts of the body.
- Check the amount of amniotic fluid. Amniotic fluid is a clear liquid that surrounds an unborn baby during pregnancy. It protects the baby from outside injury and cold. It also helps promote lung development and bone growth.
Diagnostic ultrasound may be used to:
- Find out if blood is flowing at a normal rate and level.
- See if there is a problem with the structure of your heart.
- Look for blockages in the gallbladder.
- Check the thyroid gland for cancer or non-cancerous growths.
- Check for abnormalities in the abdomen and kidneys.
- Help guide a biopsy procedure. A biopsy is a procedure that removes a small sample of tissue for testing.
In women, diagnostic ultrasound may be used to:
- Look at a breast lump to see if it might be cancer. (The test may also be used to check for breast cancer in men, though this type of cancer is far more common in women.)
- Help find the cause of pelvic pain.
- Help find the cause of abnormal menstrual bleeding.
- Help diagnose infertility or monitor infertility treatments.
In men, diagnostic ultrasound may be used to help diagnose disorders of the prostate gland.
Why do I need an ultrasound?
You may need a ultrasound if you are pregnant. There is no radiation used in the test. It offers a safe way of checking the health of your unborn baby.
You may need diagnostic ultrasound if you have symptoms in certain organs or tissues. These include the heart, kidneys, thyroid, gallbladder, and female reproductive system. You may also need ultrasound if you are getting a biopsy. The ultrasound helps your health care provider get a clear image of the area that is being tested.
What happens during an ultrasound?
A ultrasound usually includes the following steps:
- You will lie on a table, exposing the area that’s being viewed.
- A health care provider will spread a special gel on the skin over that area.
- The provider will move a wand-like device, called a transducer, over the area.
- The device sends sound waves into your body. The waves are so high pitched that you can’t hear them.
- The waves are recorded and turned into images on a monitor.
- You may be able to view the images as they are being made. This often happens during a pregnancy ultrasound, allowing you to look at your unborn baby.
- After the test is over, the provider will wipe the gel off your body.
- The test takes about 30 to 60 minutes to complete.
In some cases, a pregnancy ultrasound may be done by inserting the transducer into the vagina. This is most often done early in pregnancy.
Will I need to do anything to prepare for the test?
The preparations will depend on which type of ultrasound you are having. For ultrasounds of the abdominal area, including pregnancy ultrasounds and ultrasounds of the female reproductive system, you may need to fill up your bladder before the test. This involves drinking two to three glasses of water about an hour before the test, and not going to the bathroom. For other ultrasounds, you may need to adjust your diet or to fast (not eat or drink) for several hours before your test. Some types of ultrasounds require no preparation at all.
Your health care provider will let you know if you need to do anything to prepare for your ultrasound.
Are there any risks to the test?
There are no known risks to having an ultrasound. It is considered safe during pregnancy.
What do the results mean?
If your pregnancy ultrasound results were normal, it doesn’t guarantee you’ll have a healthy baby. No test can do that. But normal results may mean:
- Your baby is growing at a normal rate.
- You have the right amount of amniotic fluid.
- No birth defects were found, though not all birth defects will show up on an ultrasound.
If your pregnancy ultrasound results were not normal, it may mean:
- The baby is not growing at a normal rate.
- You have too much or too little amniotic fluid.
- The baby is growing outside the uterus. This is called an ectopic pregnancy. A baby can’t survive an ectopic pregnancy, and the condition can be life threatening for the mother.
- There is a problem with the baby’s position in the uterus. This could make delivery more difficult.
- Your baby has a birth defect.
If your pregnancy ultrasound results were not normal, it doesn’t always mean your baby has a serious health problem. Your provider may suggest more tests to help confirm a diagnosis.
If you had diagnostic ultrasound, the meaning of your results will depend on which part of the body was being looked at.
If you have questions about your results, talk to your health care provider.