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The first
obstetrical use of ultrasound was in 1958. Over the past 25 years,
ultrasound has become almost routine in the care of pregnant women.
Ultrasound is a method of creating an image by "bouncing" sound
waves off tissues. The current technology uses "real time"
ultrasound, meaning that you see the picture on a screen as it is
obtained. These images can also be recorded digitally, on videotape,
or in still photos.
Safety
Ultrasound in its current form seems to be completely safe for the
fetus. No risks have been demonstrated in its 25 years of common
use.
Having an ultrasound
Obstetrical ultrasound can be performed trans-abdominally (TA-US)
or trans-vaginally (TV-US).
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Trans-abdominal ultrasound: TA-US is most
useful in the second and third trimester. For a trans-abdominal
ultrasound, the technician puts a gel on your abdomen (to
transmit the sound waves) and moves the transducer (which looks
like a microphone), over your uterus to create images of the
fetus. You may be able to look at the screen and see moving (in
both meanings of the word) pictures of your baby.
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Trans-vaginal ultrasound: Trans-vaginal
ultrasound is used most commonly in the first trimester, and
sometimes as an adjunct to trans-abdominal scanning later on in
the pregnancy. The TV-US transducer is shaped like a long narrow
probe, covered with a condom for sterility, and placed in your
vagina. Gel is placed into the condom for transmission of sound
waves, and onto its outer surface for lubrication. TV-US feels a
lot like having a Pap test.
Neither type of ultrasound should be painful,
although sometimes the TA-US requires a full bladder, which can be
uncomfortable.
Who needs ultrasound?
This is a question that is being hotly debated: should ultrasound be
routine, or used only if there are questions or problems with the
pregnancy? While there isn't any research that has shown that babies
do better with routine ultrasound, many practitioners (and many
parents) still feel most comfortable if they have "seen" the fetus
before birth. Routine ultrasound is believed to be safe, but there
is a financial cost to ultrasound that may prevent it from being
used on a routine basis.
Reasons for having an ultrasound
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If the due date is unclear
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If there is vaginal
bleeding or
severe abdominal pain
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If the uterus seems too big or too small during
prenatal visits
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If there is great risk of poor fetal growth or
if growth can't be assessed adequately (as in twins or maternal
obesity)
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If there is an increased likelihood of birth
defects
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In any situation where getting an image of the
baby, placenta, uterus or cervix will clearly assist in the care
of the mother and baby
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