Ultrasound
What is ultrasound?
An
ultrasound scan is a medical test that uses high-frequency sound waves
to capture live images from the inside of your body. It’s also known as
sonography.
The technology is similar to that used by sonar and
radar, which help the military detect planes and ships. An ultrasound
allows your doctor to see problems with organs, vessels, and tissues
without needing to make an incision.
Unlike other imaging
techniques, ultrasound uses no radiation. For this reason, it’s the
preferred method for viewing a developing fetus during pregnancy.
Why an ultrasound is performed
Most
people associate ultrasound scans with pregnancy. These scans can
provide an expectant mother with the first view of her unborn child.
However, the test has many other uses.
Your doctor may order an
ultrasound if you’re having pain, swelling, or other symptoms that
require an internal view of your organs. An ultrasound can provide a
view of the:
- bladder
- brain (in infants)
- eyes
- gallbladder
- kidneys
- liver
- ovaries
- pancreas
- spleen
- thyroid
- testicles
- uterus
- blood vessels
How to prepare for an ultrasound
The steps you will take to prepare for an ultrasound will depend on the area or organ that is being examined.
Your
doctor may tell you to fast for eight to 12 hours before your
ultrasound, especially if your abdomen is being examined. Undigested
food can block the sound waves, making it difficult for the technician
to get a clear picture.
For an examination of the gallbladder,
liver, pancreas, or spleen, you may be told to eat a fat-free meal the
evening before your test and then to fast until the procedure. However,
you can continue to drink water and take any medications as instructed.
For other examinations, you may be asked to drink a lot of water and to
hold your urine so that your bladder is full and better visualized.
Be
sure to tell your doctor about any prescription drugs, over-the-counter
medications, or herbal supplements that you take before the exam.
It’s important to follow your doctor’s instructions and ask any questions you may have before the procedure.
An
ultrasound carries minimal risks. Unlike X-rays or CT scans,
ultrasounds use no radiation. For this reason, they are the preferred
method for examining a developing fetus during pregnancy.
How an ultrasound is performed
Before
the exam, you will change into a hospital gown. You will most likely be
lying down on a table with a section of your body exposed for the test.
An ultrasound technician, called a sonographer, will apply a
special lubricating jelly to your skin. This prevents friction so they
can rub the ultrasound transducer on your skin. The transducer has a
similar appearance to a microphone. The jelly also helps transmit the
sound waves.
The transducer sends high-frequency sound waves
through your body. The waves echo as they hit a dense object, such as an
organ or bone. Those echoes are then reflected back into a computer.
The sound waves are at too high of a pitch for the human ear to hear.
They form a picture that can be interpreted by the doctor.
Depending on the area being examined, you may need to change positions so the technician can have better access.
After
the procedure, the gel will be cleaned off of your skin. The whole
procedure typically lasts less than 30 minutes, depending on the area
being examined. You will be free to go about your normal activities
after the procedure has finished.
After an ultrasound
Following
the exam, your doctor will review the images and check for any
abnormalities. They will call you to discuss the findings, or to
schedule a follow-up appointment.