What is ultrasound?
How does the procedure work?
What are the common uses of this procedure?
What are the benefits of ultrasound?
Is ultrasound safe?
What are the limitations of ultrasound
imaging? |
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| What is ultrasound? |
| Ultrasound (US), also
called sonography, is a method of dynamically imaging the human body through
the use of high-frequency sound waves. A microphone-like instrument (transducer)
is scanned over the skin. Gel is placed on the skin to improve the contact
of the transducer to the area being examined. The sound waves are recorded
and displayed as a real-time visual image. US can be used to examine many
parts of the body including the abdomen, pelvis and blood vessels, as well
as the fetus during pregnancy. Because no ionizing radiation (x-ray) is
involved, ultrasound is an extremely safe imaging modality. The procedure
is painless and generally takes about 30 to 45 minutes to complete. |
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How does the procedure work? |
| Ultrasound imaging
is based on the same principles involved in the sonar used by bats or ships
at sea. As the sound passes through the body, echoes are produced that
can be used to identify how far away an object is, how large it is, its
shape and its consistency (fluid, solid or mixed). The ultrasound transducer
functions as both a generator of sound (like a speaker) and a detector
(like a microphone). When the transducer is pressed against the skin it
directs inaudible, high-frequency sound waves into the body. As the sound
echoes from the body’s fluids and tissues the transducer records
the strength and character of the reflected waves. These echoes are instantly
measured and displayed by a computer, which in turn creates a real-time
picture on the monitor. The "live" images of the examination
are usually recorded on videotape but one or more frames of the moving
picture may be "frozen" to capture a still image. |
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What are the common
uses of this procedure? |
As a diagnostic tool, ultrasound has a wide variety of uses in medicine,
including:
- Imaging of veins and arteries to see and evaluate blockages to blood
flow
- Examining many of the body's internal organs, including the heart,
liver, gallbladder, spleen, pancreas, kidneys and bladder
- Examining
the neck to help diagnose thyroid abnormalities
- Monitoring fetal development
and accessing fetal abnormalities
- Determining the cause of pelvic
pain, abnormal bleeding and other menstrual problems
- Investigating
uterine abnormalities in women who experience infertility or multiple
miscarriages
- Imaging the breast and to guide biopsy in breast cancer
- Evaluating the prostate
- Determining the source of pain, swelling
or infection in many parts of the body
- Assessing organ damage following
illness
- Revealing the shape, texture and composition of tumors and
cysts
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| What are the benefits
of ultrasound? |
Ultrasound
imaging offers these benefits:
- Provides a simple, painless and noninvasive imaging method for viewing
structures within the body
- Uses no ionizing radiation (x-rays) and
is the preferred image modality for diagnosis and monitoring of pregnant
women and their unborn infants
- Produces real-time imaging, making
it a good tool for guiding minimally invasive procedures such as needle
biopsies
- Visualizes structure, movement and live function in the body's
organs and blood vessels
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| Is ultrasound safe? |
| Since ultrasound emits
no x-rays, it is very safe. There are no known risks or side effects associated
with diagnostic ultrasound |
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What are the limitations of ultrasound imaging? |
| Ultrasound has difficulty penetrating
bone and therefore can only see the outer surface of bony structures and
not what lies within. For visualization of bone, other imaging modalities
such as magnetic resonance imaging (MRI) may be selected. Because ultrasound
waves do not pass through air, an evaluation of the stomach, small intestine
and large intestine may be limited. Intestinal gas may also prevent visualization
of deeper structures such as the pancreas and aorta. Obese patients are
also more difficult to image because tissue attenuates (weakens) the sound
waves as they pass deeper into the body. |
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| See About Your Exam/Ultrasound for
exam preparation and patient experience information. |