| Pediatric Abdominal Ultrasound Imaging
What is Abdominal Ultrasound Imaging? Back top Top
Ultrasound
imaging, also called ultrasound scanning or sonography, is a method of
obtaining images from inside the human body through the use of high
frequency sound waves. The sound waves' echoes are recorded and
displayed as a real-time visual image. No ionizing radiation is
involved in ultrasound imaging. Because ultrasound images are captured
in real time they can show movement of internal tissues and organs and
enable physicians to see blood flow. This can help to diagnose a
variety of conditions and to assess damage caused by illness.
Ultrasound is fast, accurate and painless, does not require the child
to remain still for long periods, and the equipment is less
intimidating than the large tunnels of a magnetic resonance imaging
(MRI) or computed tomography (CT) scan.
What are some common uses of the procedure? Back top Top
In
children, an abdominal ultrasound image is a useful way of examining
internal organs including the appendix, liver, gallbladder, spleen,
pancreas, intestines, kidneys and bladder. Ultrasound is particularly
valuable for evaluating abdominal pain in young children.
After
traumatic injury, appendicitis is the most common reason for emergency
abdominal surgery. Appendicitis can occur at any age but is most common
in young people ages 11 to 20. Ultrasound imaging is sometimes used to
help make the diagnosis of appendicitis in children.
Ultrasound imaging can:
- Help a physician determine the source of abdominal pain, such as stones, abscesses or an inflamed appendix.
- Guide procedures such as needle biopsies, in which needles are used to sample cells from organs for laboratory testing.
- Help identify the cause for enlargement of an abdominal organ.
- Localize abnormal fluid in the abdomen.
How should my child be prepared for the procedure? Back top Top
Your
child should be dressed in comfortable, loose-fitting clothing for an
ultrasound exam. Other preparation depends on the type of examination.
For some scans, your doctor may ask you to withhold food and drink for
as many as 12 hours before your child's appointment. For others, you
may be asked to have your child drink up to six glasses of water two
hours prior to the exam and avoid urinating so that his or her bladder
is full when the scan begins. Sedation is rarely needed for ultrasound
examinations.
What does the equipment look like? Back top Top
An
ultrasound scanner consists of a console containing a computer and
electronics, a video display screen and a transducer that is used to
scan the body. The transducer is a small, hand-held device about the
size of a bar of soap attached to the scanner by a cord. The
radiologist or sonographer spreads a lubricating gel on the child's
abdomen in the area being examined, and then presses the transducer
firmly against the skin to obtain images. The ultrasound image
is immediately visible on a nearby screen that looks much like a
computer or television monitor. The radiologist or sonographer watches
this screen during an examination; often the patient is able to see it
as well.
An example of the ultrasound equipment that may be used is shown at the top of this page.
How does the procedure work? Back top Top
Ultrasound
imaging is based on the same principles involved in the sonar used by
bats, ships at sea and fish detectors. As a controlled sound bounces
against objects, its echoing waves can be used to identify how far away
the object is, how large it is, and how uniform it is.
The
ultrasound transducer functions as both a loudspeaker to create the
sounds and a microphone to record them. When the transducer is pressed
against the skin, it directs a stream of inaudible, high-frequency
sound waves into the body. As the sound waves echo from the body's
fluids and tissues, the sensitive microphone in the transducer records
the strength and location of the reflected waves. With Doppler
ultrasound the microphone captures and records tiny changes in the
sound wave's pitch and direction. These signature waves 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 can be
recorded on videotape. In addition, still frames of the moving picture
are usually frozen to capture a series of images.
How is the procedure performed? Back top Top
Your
child is positioned on an examination table, then a clear gel is
applied to the abdomen to help the transducer make secure contact with
the skin. The sound waves produced by the transducer cannot penetrate
air, so the gel helps to eliminate air pockets between the transducer
and the skin. The sonographer or radiologist presses the transducer
firmly against the skin and sweeps it back and forth to image the area
of interest.
When the examination is complete, you and your
child may be asked to wait while the ultrasound images are reviewed
either on film or on a TV monitor. Often the sonographer or radiologist
is able to review the ultrasound images in real time as they are
acquired, and your child can be released immediately.
What will my child experience during the procedure? Back top Top
Ultrasound
imaging of the abdomen is painless, fast and easy. Your child will lie
on his or her back on an examining table. The radiologist or
sonographer will spread warm gel on the skin, then press and move the
transducer firmly against the body to capture the desired images. There
may be varying degrees of discomfort from pressure as the radiologist
or sonographer guides the transducer over the abdomen, especially if
the child has a full bladder. The examination usually takes less than
30 minutes.
Who interprets the results and how do we get them? Back top Top
A
radiologist, who is a physician experienced in ultrasound and other
radiology examinations, will analyze the images and send a signed
report with his or her interpretation to your pediatrician or primary
care physician. Your physician's office will tell you how to obtain
their results. New technology also allows for distribution of
diagnostic reports and referral images over the Internet at some
facilities.
What are the benefits vs. risks? Back top Top
Benefits
- Ultrasound provides real-time (live) imaging, making it a
good tool for quick evaluation of potentially emergent conditions such
as appendicitis.
- Ultrasound equipment is much less
intimidating to young children than the large equipment used in other
types of imaging, such as magnetic resonance imaging (MRI) or computed
tomography (CT) scans.
- Ultrasound scanning does not require a child to lie perfectly still in order to capture a useful image.
- Ultrasound imaging is a painless, low-cost and non-invasive examination.
- Ultrasound is widely available and easy to use.
- Ultrasound does not expose children to ionizing radiation.
Risks
- For standard diagnostic ultrasound there are no known harmful effects to humans.
What are the limitations of Abdominal Ultrasound Imaging? Back top Top
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 procedures such as x-ray, computed tomography
(CT) or magnetic resonance imaging (MRI) may be selected. Sound waves
do not pass through air, and evaluation of the stomach, small intestine
and large intestine may be limited by gas within these structures. Back top Top |
