Ultrasound in Pregnancy
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.
Ultrasound in its current form seems to be completely safe for the
fetus. No risks have been demonstrated in its 25 years of common
Having an ultrasound
Obstetrical ultrasound can be performed trans-abdominally
(TA-US) or trans-vaginally (TV-US).
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.
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
If the due date is unclear
If there is vaginal bleeding or
severe abdominal pain
If the uterus seems too big or too small during prenatal
If there is great risk of poor fetal growth or if growth
can't be assessed adequately (as in twins or maternal obesity)
If there is an increased likelihood of birth defects
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
Vaginal ultrasound to evaluate 1st trimester pregnancy