What is a Prenatal Ultrasound?

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  • Written By: Nat Robinson
  • Edited By: Heather Bailey
  • Last Modified Date: 15 November 2018
  • Copyright Protected:
    Conjecture Corporation
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A prenatal ultrasound, sometimes called a sonogram, is a diagnostic test that produces images of an unborn baby while still in the uterus. The images are produced by sound waves that are so high in frequency they are undetectable to the human ear. Doctors commonly use prenatal ultrasound imaging to confirm a pregnancy and to determine how far along in the pregnancy a woman is. It may also be used to examine the overall health of the developing fetus. Most pregnant women will have several prenatal ultrasounds during the course of their pregnancy.

There are several incidences in which a prenatal ultrasound may be done. The ultrasound may initially be done when a woman first suspects she is pregnant. Doctors may conduct this test to confirm the suspicion. If another test, such as a blood or urine test, confirmed the pregnancy beforehand, the ultrasound may be done to detect the gestational age of the unborn child. Doctors will also be able to confirm the location of the baby inside the womb, which is useful in detecting ectopic or tubal pregnancies.


This test can also analyze the growth and wellness of the child as well. For instance, it can be used to detect congenital abnormalities prior to birth. As the mother grows closer to the date of delivery, a prenatal ultrasound will be used to determine the fetal position. This is important to plan the best method of delivery to attempt for the safety of the mother and child. Additionally, for anxious parents eager to discover the gender of their unborn child, prenatal ultrasounds may be used to determine the baby's sex as well.

Generally, there is no certain type of preparation needed for a prenatal ultrasound. At times, doctors may request that the woman arrive at the appointment with a full bladder. Typically, this request is made for a more optimal internal view. In any event, if preparations are needed of any kind, doctors typically make them clearly known to the patient.

Most commonly, during a standard prenatal ultrasound, the woman will be asked to lie on a table and a gel will be applied to her lower abdomen. A transducer will be glided across the area and the image of the baby will appear on a neighboring video screen. Under special circumstances, the woman may be asked to have a transvaginal ultrasound. With this type of prenatal test, a small transducer will be placed into the vagina instead. Although, this is not the standard type of ultrasound testing for pregnant women, it may be used in the beginning stages of pregnancy or later for a more detailed view of the uterus and reproductive organs.

Typically, prenatal ultrasounds take about 30 minutes to complete. If the woman was asked to come to the testing center with a full bladder, she will be asked to empty it as soon as the test is finished. Doctors commonly review the results of the test as soon as it is finished. Generally, pregnant women will undergo more than one ultrasound of this kind. The time and date of a following ultrasound will generally be revealed by the supervising physician.



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