Ultrasound (cont.)
For what purposes are ultrasounds used?
Ultrasound is not limited to diagnosis, but can also be used in screening for
disease and to aid in treatment of diseases or conditions.
Diagnostic uses
Obstetrics
Ultrasound routinely for assessing the progression of
pregnancy. Pelvic ultrasounds can be obtained trans-abdominally where the probe
is placed on the abdominal wall, or trans-vaginally, where the probe is placed in the vagina. For
example ultrasound in obstetrics is used to diagnose growths or tumors of the
ovary,
uterus,
Fallopian tubes.
Cardiology
Echocardiography
Echocardiography
(echo=sound + cardio=heart + graphy=study) evaluates the heart, the heart's valve
function, and blood flow through them. It also evaluates the heart wall motion and the amount of blood
the heart pumps with each stroke.
Echocardiography can be performed in two ways:
- trans-thoracic: the probe is place on chest wall to obtain images, and
- trans-esophageal: where the probe is placed through the mouth into the
esophagus.
Anatomically, the
esophagus sits near the heart and allows clearer images. However, this approach
is a little more invasive.
Different groups of illnesses can be assessed by echocardiography:
- Valves in the heart keep blood flowing in one direction when the heart
pumps. For example, when the heart beats, blood is pumped from the left
ventricle through the aortic valve into the aorta and the rest of the body.
The aortic valve prevents blood from back-flowing into the heart as it fills
for the next beat. Echocardiography can determine if the valve is narrow or
leaking (regurgitating, insufficient). By following how the patient fares
clinically, repeated echocardiograms can help determine whether valve
replacement or repair is warranted. The same principles apply to the
mitral
valve which keeps blood flowing from the left atrium to the left ventricle.
- The heart muscle pumps
blood to the body. If the heart weakens, the amount of blood it pumps with each beat
can decrease, leading to congestive heart failure. The echocardiogram can
measure the efficiency of the heart beat and how much blood it pumps; which
assists in determining whether medications are needed. It also is used to monitor how
well
medications are working.
- Echocardiography can visualize the heart chambers to detect blood clots
in conditions such as atrial fibrillation
(an irregular heart rhythm). In other situations, the test can help diagnose
endocarditis (an
infection of the heart valves) by visualizing "vegetations" (an infected mass) on the valves
themselves.
- Echocardiography also can detect abnormal fluid collections (pericardial
effusions) in the pericardium.
- Echocardiograms are used to diagnose and monitor
pulmonary artery
hypertension.
Blood vessels
Ultrasound can detect blood clots in veins (superficial or deep venous thrombosis)
or artery blockage (stenosis) and
dilatation (aneurysms). Some examples of
ultrasound testing include:
- Carotid ultrasound is performed in patients with
transient ischemic
attacks (TIAs) or strokes to determine whether the major arteries in the neck are blocked
causing the decreased blood supply to the brain.
- The aorta is the large blood vessel leaving the heart
that supplies blood to the rest of the body. The walls of the aorta are under
significant pressure from the force of the heartbeat and over time, may weaken
and widen. This is called an aneurysm, and it can be detected in the abdomen by
ultrasound (abdominal aortic
aneurysm). For those patients with small aneurysm, observation may be
recommended and the aneurysm size followed over time by repeated tests.
- Veins can also be evaluated by ultrasound and it is a
common test to assess whether swelling in a leg is due to a blood clot,
deep vein thrombosis (DVT) or another
cause.
Abdominal structures
Aside from its use in obstetrics, ultrasound can
evaluate most of the solid structures in the abdominal cavity. This includes the
liver, gallbladder,
pancreas, kidneys,
bladder,
prostate,
testicles, uterus, and ovaries.
- Ultrasound is the preferred to test to screen for
gallstones or an infected gallbladder. The ultrasound can reveal the stones as
well as signs of infection, including thickening of the gallbladder wall and
fluid surrounding the gallbladder. The ultrasound may find blockage in the
bile ducts.
- For those patients where the radiation of a
CT scan (computerized tomography) is a potential risk (pregnant patients or
children), ultrasound may be used to look for diseases like
appendicitis or
kidney stones.
- Ultrasound is the test of choice to diagnose
testicular torsion.
- Pelvic ultrasound is used in gynecology to help
assess non-pregnancy related issues like lower abdominal pain, ovarian cysts,
uterine fibroids, uterine
growths, and
endometriosis.
The neck
The thyroid gland can be imaged using ultrasound looking for
nodules, growths, or tumors.
Knee joint
Ultrasound can
be used to detect bulging of fluid from a swollen knee joint into the back of
the knee, called a Baker's cyst.
Next: Screening uses »