11. Ultrasound in Pregnancy
By this point, you may have discussed
ultrasound with your healthcare provider. Or you may already have had an
ultrasound test. Ultrasound (also called sonography or sonogram)
is one of our most valuable tools for evaluating a pregnancy.
Healthcare providers, hospitals and insurance companies (yes, they get
involved in this too) don’t agree whether ultrasound should be done or
if every pregnant woman needs an ultrasound test during pregnancy. It is
a noninvasive test, and there are no known risks associated with it. In
the United States, millions of obstetrical ultrasounds are performed
each year!
Ultrasound involves the use of
high-frequency sound waves made by applying an alternating current to a
transducer. A lubricant is rubbed on the skin to improve contact with
the transducer. The transducer passes over the tummy, above the uterus.
Sound waves are sent from the transducer through the tummy, into the
pelvis. As sound waves bounce off tissues, they are directed toward and
back to the transducer. The reflection of sound waves can be compared to
“radar” used by airplanes or ships.
Different tissues of the body reflect
ultrasound signals differently, and we can distinguish among them.
Motion can also be seen, so we can detect motion of
the baby or parts of the baby, such as the heart. With ultrasound, a
fetal heart can be seen beating as early as 5 or 6 weeks into the
pregnancy. Your baby’s body and limbs can be seen moving as early as 4
weeks of embryonic growth (6th week of pregnancy).
Your healthcare provider uses ultrasound in many ways in relation to your pregnancy, such as:
• helping in the early identification of pregnancy
• showing the size and growth rate of the baby
• identifying the presence of two or more babies
• measuring the fetal head, abdomen or femur to determine the stage of pregnancy
• identifying some fetuses with Down syndrome
• identifying some birth defects
• identifying some internal-organ problems
• measuring the amount of amniotic fluid
• identifying the location, size and maturity of the placenta
• identifying placental abnormalities
• identifying uterine abnormalities or tumors
• determining the position of an IUD
• differentiating between miscarriage, ectopic pregnancy and normal pregnancy
• in connection with various tests,
such as amniocentesis, percutaneous umbilical-cord blood sampling (PUBS)
and chorionic villus sampling (CVS), to select a safe place to do each
test
You may be asked to drink a lot of water
before an ultrasound examination. Your bladder is in front of your
uterus. When your bladder is empty, your uterus is harder to see because
it’s farther down inside the pelvic bones. Bones disrupt ultrasound
signals and make the picture harder to interpret. With your bladder
full, your uterus rises out of the pelvis and can be seen more easily.
The bladder acts as a window to look through to see the uterus and the
fetus inside.
Other Ultrasound Tests. The ultrasound vaginal probe, also called the transvaginal ultrasound, can be used in early pregnancy for a better view of the baby and placenta. A probe is placed inside the vagina, and the pregnancy is viewed from this angle.
The UltraScreen test identifies
babies at increased risk of having certain birth defects. The test
combines maternal blood tests and an ultrasound measurement at 11 to 13
weeks. The UltraScreen test is fairly effective in detecting Down
syndrome.
Fetal nasal-bone evaluation is
another type of ultrasound exam that increases Down syndrome detection
accuracy to 95%, with a small percentage of false-positives. The benefit
of first trimester screening is earlier diagnosis.
Three-dimensional ultrasound is also available in many areas.
Can Ultrasound Determine the Baby’s Sex?
Some couples ask for ultrasound to determine whether they are going to
have a boy or girl. If the baby is in a good position and it’s old
enough for the genitals to have developed and they can be seen clearly,
determination may be possible. However, many healthcare providers feel
this reason alone is not a good reason to do an ultrasound exam. Discuss
it with your healthcare provider. Understand ultrasound is a test, and
test results can occasionally be wrong.
12. Fetal MRI
Ultrasound is the standard test used to
diagnose birth defects and other problems. It is often the first test
used. However, there are some limitations to ultrasound. If a woman is
obese, if there is less amniotic fluid or baby is in an abnormal
position, ultrasound may not reveal problems. In addition, midpregnancy
is the best time to use ultrasound, so earlier or later use may not be
as helpful.
Tip for Week 11
You may be able to get a “picture” of
your baby before birth from an ultrasound test. Some facilities can even
make a DVD or videotape for you. Ask about it before the test, if
you’re scheduled to have one.
Relax and Have a Great Pregnancy!
It’s natural to feel nervous about being
pregnant and what lies ahead—labor and delivery, and going home with
baby. It’s important to deal with any anxieties you may have, and focus
on having a great pregnancy. Below are some guidelines to help you do
just that.
• Don’t panic if someone bumps you in the tummy. Your baby is well protected.
• It’s OK to lift things—just
don’t lift heavy objects. Sacks from the market and a young child won’t
hurt you. Stay away from heavy lifting.
• You don’t have to worry about
using a computer, a cell phone, a microwave oven or going through
airport security. None of the machines involved in these procedures
produce enough “bad vibes” to hurt you or your baby.
• Coloring or perming your hair is
OK. The chemicals used in these preparations won’t hurt you. However,
if the fumes make you sick, wait until you aren’t bothered so much by
smells to have a perm or color your hair.
• Ask your partner to take
pictures of you as you move through pregnancy. It’s fun to look back at
them and remember how big you were when.
• Even though you may not feel
sexy, wear a beautiful, supportive bra made for expecting moms. It can
help you feel pretty and desirable (which you are anyway!). For added
comfort for your breasts, check out sleep bras. They can add support to
sore breasts while you sleep.
• Pamper your feet. Wear good,
comfortable shoes. Get a pedicure or foot massage. Soak your feet when
they’re sore. Use foot cream to help
Another test healthcare providers use has
fewer limitations—fetal MRI. Fetal MRI (magnetic resonance imaging) is
most helpful when findings from ultrasound are unclear or cannot be seen
clearly.
MRI does not use radiation. Several
studies have shown MRI is safe to use during pregnancy. To be cautious,
MRI is still not advised during the first trimester. The test is most
useful in diagnosing babies with specific birth defects.
It is important to note that
ultrasound is more widely available and lower in cost than MRI.
Ultrasound is still the first choice for discovering problems. However,
MRI can be helpful in special situations, as mentioned above.
13. Exercise for Week 11
Place your left hand on the back of a
chair or against the wall. Lift your right knee up, and put your right
hand under your thigh. Round your back, and bring your head and pelvis
forward. Hold position for count of 4, straighten up, then lower your
leg. Repeat with your left leg. Do 5 or 8 times with each leg. Reduces back tension, and increases blood flow to the feet.
