Fetal ultrasound is a test done during pregnancy that uses
reflected sound waves to produce a picture of a
fetus , the organ that nourishes the fetus (placenta), and the liquid that surrounds the fetus
(amniotic fluid). The picture is displayed on a TV
screen and may be in black and white or in color. The pictures are also called
a sonogram, echogram, or scan, and they may be saved as part of your baby's
Fetal ultrasound is the safest way to check for problems
and get information about your fetus, such as its size and position. It does
X-rays or other types of radiation that may harm your
fetus. It can be done as early as the 5th week of pregnancy. The sex of your
fetus can sometimes be determined by about the 18th week of pregnancy.
- Pregnancy: Should I Have an Early Fetal Ultrasound?
A combination of screening tests using ultrasound may be
done in the first
trimester to look for
birth defects, such as Down syndrome. The
first-trimester screening test uses an ultrasound measurement of the
thickness of the skin at the back of the baby's neck (nuchal translucency) and
the blood levels of free beta-HCG and a protein called pregnancy-associated
plasma protein A (PAPP-A) to check for problems.
Sarah Marshall, MD - Family Medicine
William Gilbert, MD - Maternal and Fetal Medicine
June 18, 2012
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