Pregnancy Health: How Ultrasounds Work, And What They Can Show

What does an ultrasound screening show, and is it safe for your developing baby? Find out the uses and benefits of this commonly-used test.

Ultrasounds, also known as sonograms, are commonly used in pregnancy for a variety of reasons.This type of testing works by recording the echoes of sound waves as they bounce off of the fetus; the sound waves are then translated into a kind of topographical map of the fetus that the ultrasound technician can view on a screen.Sonography is safe, with no known risks or side effects to the mother or baby, and offers a great deal of information that can help the obstetrician either identify potential problems or simply verify that a pregnancy is proceeding normally (which has the added benefit of providing the jittery expectant mother with much-needed peace of mind).

A pregnant woman can expect to go for a routine ultrasound at about 22 weeks of pregnancy.To make the uterus more accessible, the bladder should be full - so your doctor will tell you in advance how much water to drink about an hour before the test.The woman lies on her back, and a thin layer of ultrasound gel is spread on her abdomen.Then the technician moves a handheld instrument called a transducer over the abdomen as he or she views the image of the fetus on the screen.The test is not painful or intrusive, but may be uncomfortable due to the mother's full bladder.Fortunately, most ultrasound technicians will allow the mother to go to the restroom after the first part of the screening.

During a routine ultrasound screening, the technician will check (and possibly adjust) the due date based on the baby's size; listen to the heartbeat; check the fetus for any abnormalities; and, if you request it, try to determine the baby's sex.(Most technicians will not tell the mother the sex of the baby unless she asks.Even if you do ask and receive an answer, keep in mind that the answer may not be 100% reliable.)


In the course of a normal pregnancy with no complications, only one ultrasound test (at 22 weeks) should be necessary.However, an earlier ultrasound may be ordered if the doctor is unable to detect the baby's heartbeat with a handheld Doppler device by about the 14th week of pregnancy.Later in the pregnancy, if the woman's uterus seems to grow unusually fast from one visit to another, an ultrasound may be used to determine if the rapid growth is caused by an excess of amniotic fluid.

Among the many other uses of the ultrasound screening are: detecting the presence of multiple fetuses; determining the location and position of the fetus before amniocentesis or chorionic villus sampling (tests performed to detect genetic abnormalities); locating an IUD that was in place prior to the pregnancy; and determining whether a baby's position is breech prior to delivery.

Of course, the many uses of sonography aside, one of the most thrilling aspects of an ultrasound screening is the chance for the mother to see her little one in action - sucking its thumb, kicking, squirming, and crossing its legs.If the image is relatively clear, be sure to ask for a souvenir printout you can share with family and friends!

Again, most ultrasound screenings are routine and simply verify the due date and provide reassurance that the baby is normal.So relax and enjoy this safe, painless test and the peace of mind it brings - and good luck with your pregnancy.

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