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What is prenatal ultrasound?
Like other ultrasound examinations, prenatal or fetal ultrasound uses high-frequency sound waves to obtain images of the fetus, placenta, and amniotic sac in a pregnant woman. The test does not involve radiation and is completely safe for both mother and baby. An ultrasound examination is also known as a sonogram. The entire procedure can be performed in 30 minutes or less. Two types of ultrasound exams are used in pregnancy.
Two types of ultrasound exams are used in pregnancy. The most common is a transabdominal ultrasound, in which the measuring instrument (transducer) is moved over the surface of the abdomen after a gel has been applied. Sometimes a full bladder is required to obtain better images, so you may be asked to drink several glasses of water before the test. There is no pain or discomfort associated with the test, and it can be performed in the doctor's office.
Transvaginal ultrasound uses a probe that is inserted directly into the vagina. It is performed in the doctor's office similar to a pelvic examination. This type of exam is most commonly used in the early weeks of pregnancy to rule out suspected problems or to assess the gestational age of the embryo. In early pregnancy this examination can provide more accurate information then a transabdominal examination.
Why is prenatal ultrasound performed?
As mentioned above, transvaginal ultrasound is most often used in the early weeks of pregnancy to rule out problems or to determine how far along you are in the pregnancy. Most pregnant women receive a transabdominal ultrasound around the 20th week of pregnancy. This exam confirms that the baby is growing normally and that the placenta is attached normally. The heartbeat of the fetus is visible, and the movement of the fetus can be observed. Major birth defects can be visualized by this method, as well. In most cases, it is possible to determine the sex of the baby through an ultrasound exam at 20 weeks, but this method is not 100% accurate. You can tell the examiner whether or not you wish to know the gender of your baby at the time of the examination.
Ultrasound may also be performed earlier or later in the pregnancy for specific reasons that include:
- Determination of multiple gestation
- Ensuring the health of the baby and monitoring its growth
- Determining the location of the placenta
- Estimation of gestational age and due date
- Assessing the expected size and weight of the baby
- Determining the amount of amniotic fluid
- Determining the position of the baby
What are 3D and 4D ultrasound?
A 3D ultrasound provides a particularly clear image that resembles a photograph. A so-called 4D ultrasound provides this image in real time. Sometimes these ultrasound images are offered by non-medical providers in stores or other locations. Medical authorities, including The American College of Obstetricians and Gynecologists and the Food and Drug Administration do not recommend using these services because the examiners may not have received proper training and could provide inaccurate information.
Are there risks associated with prenatal ultrasound?
As mentioned before, there is no radiation exposure during a prenatal ultrasound. Ultrasound exams have been used for many years, and studies have never shown any harms associated with the procedure, either on a short- or long-term basis.
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"Ultrasound During Pregnancy." March of Dimes. Updated Oct. 2014.
Top Prenatal Ultrasound Related Articles
AchondroplasiaA common form of short stature, achondroplasia (dwarfism) is a genetic condition causing a disorder of bone growth. Complications of achondroplasia that need monitoring include (this is not all inclusive) stenosis and compression of the spinal cord, a large opening under the skull, lordosis, kyphosis, spinal stenosis, hydrocephalus, middle ear infections, obesity, and dental crowning. Achondroplasia is caused by mutations of the FGFR3 gene.
Birth DefectsBirth defects have many causes and currently, are the leading cause of death for infants in the first year of life. Some of the causes of birth defects include genetic or chromosome problems. Exposure of the mother to rubella or German measles during pregnancy, or using drugs or alcohol during pregnancy. The treatment for birth defects depends upon the condition of the effected child.
Bladder CancerTreatment for bladder cancer depends on the stage of the disease, the grade of the tumor, and the type of bladder cancer. Options for treatment include surgery, radiation therapy, chemotherapy, and biological therapy.
Cerebral PalsyCerebral palsy (CP) is an abnormality of motor function and postural tone acquired at an early age (even before birth). Cerebral palsy is generally caused by brain trauma. Types of cerebral palsy include: spastic, dyskinetic (dystonic or choreoathetoid), hypotonic, and mixed types. There is no cure for cerebral palsy, and treatment is generally managing the symptoms of the condition.
Down Syndrome OverviewGet the facts on Down syndrome, a genetic disorder caused by an additional set of chromosomes in a developing fetus. Down syndrome signs and symptoms include:
- distinctive facial features,
- growth retardation, and
- decreased mental function and IQ.
Pregnancy Symptoms QuizWhat are early pregnancy symptoms? In some women, symptoms range from a missed period to feeling lightheaded. Others may experience typical "morning sickness" and food cravings. Could you be pregnant? Take the quiz!
Fetal DevelopmentTake a peek inside the womb to see the stages of fetal development. Learn how embryos develop and grow during pregnancy. See month by month ultrasound images of your baby in the womb.
Pregnancy: Multiple Births, Twins, Triplets, and MoreMultiple births occur when a woman bears twins, triplets, or even more babies during pregnancy. More multiples are born today thanks to assisted reproductive technology (ART), including in vitro fertilization using fertility drugs. Women carrying multiples often give birth via C-section.
Pregnancy Drug DangersTaking prescription medications or over-the-counter drugs or supplements should be discussed with your doctor. There are some medications that have been found to cause no problems in pregnancy, however, medications such as Accutane for acne, should never be taken during pregnancy.
Pregnancy Planning (Preparing for Pregnancy)
Pregnancy planning is an important step in preparation for starting or expanding a family. Planning for a pregnancy includes:
- Taking prenatal vitamins
- Eating healthy for you and your baby
- Disease prevention (for both parents and baby) to prevent birth defects and infections
- Avoiding certain medications that may be harmful to your baby
- How much weight gain is healthy
- Exercise safety and pregnancy
- Travel during pregnancy
Spina Bifida and AnencephalySpina bifida is the most common neural tube defect in the United States. There are four types of spina bifida; 1) occulta, 2) closed neural tube defects, 3) meningocele, and 4) myelomeningocele. The cause of spina bifida is not known. Theories include genetic, nutritional, and environmental factors. Lack of folic acid during pregnancy is highly suspected. Symptoms of spina bifida vary from individual to individual. Treatment depends on the type of spina bifida the person suffers.
Stages of PregnancySee pictures on the various stages of pregnancy. See and learn what changes a woman's body goes through and view fetal images of how her baby grows during the 1st, 2nd and 3rd trimesters.
UltrasoundUltrasound (and ultrasonography) is imaging of the body used in the medical diagnosis and screening of diseases and conditions such as:
- heart valve irregularities,
- carotid artery disease,
- heart disease,
- kidney stones,
- liver disease,
- diseases of the female reproductive, and
- diseases of the male reproductive organs.
X-rays are a powerful form of electromagnetic radiation that has the ability to pass through solid objects. In medicine, X-rays are used to obtain an image of a part of the body. X-rays are necessary to diagnose many illnesses, for example,
- dental problems,
- digestive or heart problems, and
- bone fractures.
The side effects, dangers, and risks of having X-rays while pregnant or breastfeeding are provided.