Test Overview
An abdominal
ultrasound uses reflected sound waves to produce a
picture of the organs and other structures in the upper abdomen. Sometimes a
specialized ultrasound is ordered for a detailed evaluation of a specific
organ, such as a kidney ultrasound. An abdominal ultrasound can evaluate
the:
- Abdominal
aorta, which is the large blood vessel (artery) that
passes down the back of the chest and abdomen. The aorta supplies blood to the
lower part of the body and the legs.
- Liver, which is
a large dome-shaped organ that lies under the rib cage on the right side of the
abdomen. The liver produces bile (a substance that helps digest fat), stores
sugars, and breaks down many of the body's waste products.
- Gallbladder, which is a small sac-shaped organ beneath the
liver that stores bile. When food is eaten, the gallbladder
contracts, sending bile into the intestines to help in digesting food and
absorbing fat-soluble vitamins.
- Spleen, which
is the soft, round organ that helps fight infection and filters old red blood
cells. The spleen is located to the left of the stomach, just behind the lower
left ribs.
- Pancreas, which
is the gland located in the upper abdomen that produces
enzymes that help digest food. The digestive enzymes
are then released into the intestines. The pancreas also releases
insulin into the bloodstream. Insulin helps the body
use sugars for energy.
- Kidneys, which
are the pair of bean-shaped organs located behind the upper abdominal cavity.
The kidneys remove wastes from the blood and produce urine.
A pelvic ultrasound evaluates the structures and organs in
the lower abdominal area (pelvis).
Why It Is Done
Abdominal ultrasound is done to:
- Find the cause of abdominal
pain.
- Find, measure, or monitor an
aneurysm in the aorta. An aneurysm may cause a large,
pulsing lump in the abdomen.
- Check the size, shape, and position of
the liver. An ultrasound may be done to evaluate
jaundice and other problems of the liver, including
liver masses,
cirrhosis, fat deposits in the liver (called fatty
liver), or abnormal liver function tests.
- Detect
gallstones, inflammation of the gallbladder
(cholecystitis), or blocked bile ducts. See a picture of a
gallstone.
- Learn the size of an
enlarged spleen and look for damage or disease.
- Find problems
with the pancreas, such as
a pancreatic tumor.
- Look for blocked urine flow in a kidney. A kidney
ultrasound may also be done to find out the size of the kidneys, detect kidney
masses, detect fluid surrounding the kidneys, investigate causes for recurring
urinary tract infections, or check the condition of
transplanted kidneys.
- Find out whether a mass in any of the
abdominal organs (such as the liver) is a solid tumor or a simple fluid-filled
cyst.
- Guide the placement of a needle or other instrument
during a
biopsy.
- Look for fluid buildup in the
abdominal cavity (ascites). An ultrasound also may be done to guide the
needle during a procedure to remove fluid from the abdominal cavity (paracentesis).
How To Prepare
Tell your doctor if you have had a
barium enema or a series of upper GI
(gastrointestinal) tests within the past 2 days. Barium that remains in the
intestines can interfere with the ultrasound test.
Other
preparations depend on the reason for the abdominal ultrasound test you are
having.
- For ultrasound of the liver, gallbladder,
spleen, and pancreas, you may be asked to eat a fat-free meal on the evening
before the test and then to avoid eating for 8 to 12 hours before the
test.
- For ultrasound of the kidneys, you may not need any special
preparation. You may be asked to drink 4 to 6 glasses of liquid (usually juice
or water) about an hour before the test to fill your bladder. You may be asked
to avoid eating for 8 to 12 hours before the test to avoid gas buildup in the
intestines. Gas could interfere with the evaluation of the kidneys, which lay
behind the stomach and intestines.
- For ultrasound of the aorta, you
may need to avoid eating for 8 to 12 hours before the test.
How It Is Done
This test is done by a doctor who
specializes in performing and interpreting imaging tests (radiologist) or
by an ultrasound technologist (sonographer) who is supervised by a radiologist.
It is done in an ultrasound room in a hospital or doctor's office.
You will need to take off any jewelry that might interfere with the
ultrasound scan. You will need to take off all or most of your clothes,
depending on which area is examined (you may be allowed to keep on your
underwear if it does not interfere with the test). You will be given a cloth or
paper covering to use during the test.
You will lie on your back
(or on your side) on a padded exam table. Warmed gel will be spread on your
abdomen to improve the quality of the sound waves. A small handheld unit
called a transducer is pressed against your abdomen and moved back and forth
over it. A picture of the organs and blood vessels can be seen on a video
monitor.
You may be asked to change positions so more scans can
be done. For a kidney ultrasound, you may be asked to lie on your
stomach.
You need to lie very still while the ultrasound scan is
being done. You may be asked to take a breath and hold it for several seconds
during the scanning. This lets the sonographer see organs and structures, such
as the bile ducts, more clearly because they are not moving. Holding your
breath also temporarily pushes the liver and spleen lower into the belly so
they are not hidden by the lower ribs, which makes it harder for the
sonographer to see them clearly.
Abdominal ultrasound usually
takes 30 to 60 minutes. You may be asked to wait until the radiologist has
reviewed the information. The radiologist may want to do more ultrasound views
of some areas of your abdomen.
How It Feels
Unless the gel is first warmed to body
temperature, it may feel cold when it is applied to your stomach. You will feel
light pressure from the transducer as it passes over your abdomen. The
ultrasound usually is not uncomfortable. But if the test is being done to check
damage from a recent injury, the slight pressure of the transducer may be
somewhat painful. You will not hear or feel the sound waves.
Risks
There are no known risks from having an abdominal
ultrasound test.
Results
An abdominal
ultrasound uses reflected sound waves to produce a
picture of the organs and other structures in the abdomen.
Abdominal ultrasoundNormal: | The size and shape of the
abdominal organs appear normal. The liver, spleen, and pancreas appear normal
in size and texture. No abnormal growths are seen. No fluid is found in the
abdomen. |
|---|
The diameter of the aorta is
normal and no
aneurysms are seen. |
The thickness of the
gallbladder wall is normal. The size of the bile ducts between the gallbladder
and the small intestine is normal. No
gallstones are seen. |
The kidneys appear as sharply outlined
bean-shaped organs. No
kidney stones are seen. No blockage to the system
draining the kidneys is present. |
Abnormal: | An organ may appear abnormal because of
inflammation, infection, or other diseases. An organ may be smaller than normal
because of an old injury or past inflammation. An organ may be pushed out of
its normal location because of an abnormal growth pressing against it. An
abnormal growth (such as a tumor) may be seen in an organ. Fluid in the
abdominal cavity (ascites) may be seen. |
|---|
The aorta is enlarged, or an aneurysm is
seen. |
The liver may appear abnormal, which may
point to liver disease (such as
cirrhosis or cancer). |
The walls of the gallbladder may be
thickened, or fluid may be present around the gallbladder, which may point to
inflammation. The bile ducts may be enlarged because of blockage (from a
gallstone or an abnormal growth in the pancreas). Gallstones may be seen inside
the gallbladder. |
The kidneys or the tubes that drain the
kidneys (ureters) may be enlarged because of urine that is not
draining properly. Kidney stones are seen within the kidneys (not all stones
can be seen with ultrasound). |
An area of infection (abscess) or a fluid-filled
cyst may appear as a round, hollow structure inside an
organ. The spleen may be ruptured (if an injury to the abdomen has
occurred). |
What Affects the Test
Reasons you may not be able to
have the test or why the results may not be helpful include:
- Stool, air (or other gas), or
contrast material (such as barium) in the stomach or
intestines.
- Not being able to remain still during the
test.
- Extreme
obesity.
- Having an open or bandaged wound
in the area being viewed.
What To Think About
- Other tests, such as a
computed tomography (CT) scan, may be needed to follow
up abnormal ultrasound results. For more information, see the topic
Computed Tomography (CT) Scan.
- X-rays are not recommended during pregnancy because of
the risk of damage to the
fetus. Because ultrasound is safe during pregnancy, it
generally is used instead of an abdominal X-ray if a pregnant woman's abdomen
needs to be checked.
- In rare cases, gallstones may not be found
by ultrasound. Other imaging tests may be done if gallstones are suspected but
not seen on the ultrasound. For more information, see the topics
Gallbladder Scan,
Endoscopic Retrograde Cholangiopancreatogram (ERCP),
and
Abdominal X-ray.
- Using abdominal
ultrasound, a doctor can usually distinguish among a simple fluid-filled cyst,
a solid tumor, or another type of mass that needs further evaluation. If a
solid tumor is found, abdominal ultrasound cannot determine whether it is
cancerous (malignant) or noncancerous (benign). A
biopsy may be needed if a tumor is found. Ultrasound
may be used during the biopsy to help guide the placement of the
needle.
- Ultrasound is less expensive than other tests, such as a CT
scan or
magnetic resonance imaging (MRI) scan, that also can
provide a picture of the abdominal organs. But for some problems, such as
abdominal masses or an injury, a CT scan or MRI may be a more appropriate test.
Also, these tests may be done if the abdominal ultrasound is normal but
abdominal pain persists. For more information, see the topics
Computed Tomography (CT) Scan of the Body and
Magnetic Resonance Imaging (MRI) of the Abdomen.
- A pelvic ultrasound will be used to produce a
picture of the lower abdominal (pelvic) organs and other structures inside the
pelvis. For more information, see the topic
Pelvic Ultrasound.
References
Other Works Consulted
- Fischbach FT, Dunning MB III, eds. (2009).
Manual of Laboratory and Diagnostic Tests, 8th ed.
Philadelphia: Lippincott Williams and Wilkins.
- Pagana KD, Pagana TJ (2010). Mosby’s Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby Elsevier.
Credits
| By | Healthwise Staff |
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| Primary Medical Reviewer | Kathleen Romito, MD - Family Medicine |
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| Specialist Medical Reviewer | Howard Schaff, MD - Diagnostic Radiology |
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| Last Revised | December 5, 2010 |
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