Ultrasound
(US) imaging utilizes high
frequency sound waves
to evaluate structures within the
body. A small hand-held
probe is pressed against the skin,
emitting sound waves that
cannot be heard. These waves are
reflected by different
tissues within the body, and advanced
computer processing is
used to create images of the inside
of the body. Unlike
conventional x-rays and CT scanning,
sonography does not use
radiation, making it a favorite imaging
modality in pregnant
women and in the pediatric population.
Ultrasound is frequently
used to image the abdominal
organs,
including the liver, pancreas, spleen,
and gallbladder when
patients have pain or laboratory
abnormalities. Ultrasound
remains the most sensitive test for
finding gallstones, and it is
a fast, non-invasive way of evaluating
the kidneys and bile
ducts for obstruction.
While US visualization
of structures deep within
the body may
be limited by excessive body fat
or gas within the bowel,
ultrasound is highly effective at
evaluating superficial
structures, including the thyroid
gland, the breasts, and the
testicles.
An advantage of ultrasound
is its ability to detect
and analyze
motion. This allows for evaluation
of blood flow within
arteries, veins, and surgically-created
grafts. Ultrasound is
commonly used to assess the veins
of the legs to look for
potentially lethal blood clots which
could dislodge and migrate
to the lungs. Ultrasound is also
frequently used to screen for
dangerous enlargement of the aorta
(aneurysm) in at-risk
populations.
Ultrasound is the initial
imaging modality of choice
for
evaluation of the female pelvis—providing
a detailed look at
the uterus and the ovaries. Perhaps
the best known
application of ultrasound is in the
evaluation of the pregnant
woman. US is well-suited to evaluate
the growing fetus,
surrounding amniotic fluid, and the
placenta. Ultrasound may
be utilized to evaluate fetal size,
position, movement and
heart rate. In addition to imaging
with a probe pressed against
the skin of the lower abdomen, some
examinations of the
female pelvis require use of a transvaginal
probe, which the
patient inserts into the vaginal
canal. This allows for much
more detailed imaging of the uterus
and ovaries, particularly
in patients who are not pregnant
or are in the early stages of
pregnancy.
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