An ultrasound is one of the tests you may have when you become pregnant. This prenatal test is a useful tool for monitoring your baby’s health and development. It can also evaluate your reproductive organs, such as the length of your cervix—a factor that is related to premature births. Most women have at least one prenatal ultrasound during their pregnancy, but that number varies based on other prenatal tests and your individual circumstances.
Ultrasound has been used for decades with little risk to women and their unborn babies. When performed by qualified medical professionals, ultrasounds are considered safe because they use sound waves rather than radiation to get a picture of your baby in the womb. Even so, they are only recommended when your doctor believes they are medically necessary. Although ultrasound is considered standard care for many pregnant women, it is an optional test and you can choose not to have it.
If your physician suggests an early ultrasound, it will be done in the first trimester of your pregnancy. A standard ultrasound is completed in the second trimester at 18 to 20 weeks gestational age—the amount of time that has passed since a baby was conceived.
Ultrasound can be used in several ways, such as:
Additional ultrasounds may be recommended during your second (12 to 24 weeks) or third (24 to 40 weeks) trimester for high-risk pregnancies, multiple births or to detect any abnormal development. Your physician compares ultrasound results to other tests, such as prenatal blood tests to decide whether additional diagnostic or screening tests may be needed.
Although a standard 2-D ultrasound is most common, there are six more types of ultrasound and each is used for different reasons.
Whichever method is used, the goal is always to make sure you and your baby receive the right care at the right time in your pregnancy. The information can also help maternal-fetal specialists and obstetricians work with you to plan your pregnancy and delivery. Combined with other test results, an ultrasound may change the type of delivery you have, and it may allow specialists at Riley at IU Health to plan immediate care for your child at birth, if necessary.
Most standard ultrasounds are transabdominal—which means the abdomen is the site where the probe will transmit sound waves. You will rest on your back while your abdomen is exposed, cleansed and covered with a clear gel. The purpose of the gel is to help transmit sound waves. Your healthcare provider will slide a handheld transducer over your belly to capture pictures of your baby, which can be seen on a computer monitor. Other than the pressure you may feel over your belly, you should have little or no discomfort.
If you have a transvaginal ultrasound, you will start the test with a full bladder. (Transvaginal means the probe introduces sound waves through the vagina.) You will undress below the waist and be covered with a sheet for your privacy. While you rest on your back with your feet in stirrups, your provider slides a small probe into your vagina. There is very little discomfort other than the pressure from the transducer.
Both tests take approximately 20 minutes.
The results of an ultrasound will be read by your doctor and shared with you within a few days of your test. In some cases, results are available to you immediately afterwards.
If your results are normal and your pregnancy is not considered high risk, you will continue having regular prenatal checkups for the rest of your pregnancy with no additional ultrasounds. If your initial ultrasound shows a cause for concern, your physician will likely order additional tests to help confirm or rule out problems. This may include additional ultrasounds later in your pregnancy.
Occasionally, an ultrasound suggests a problem when there is none, causing anxiety for expectant parents. Physicians at Riley at IU Health can guide you through this period and coordinate any follow-up care and testing you or your baby may need. If your baby is diagnosed with a disorder or a genetic condition, Riley at IU Health offers a multidisciplinary team of maternal-fetal specialists and genetic counselors that can provide compassionate support and expert care before, during or after birth.
There is also a possibility that an ultrasound can miss certain disorders, such as Down syndrome or birth defects. For the sake of accuracy, ultrasound is always paired with other forms of prenatal screening.
These valuable resources can help expectant parents become more informed about prenatal tests.
Riley at IU Health offers a broad range of supportive services to make life better for families who choose us for their children's care.
FamilyDoctor.org is published by the AAFP and shares public health information such as content about prenatal ultrasound.
This U.S. Department of Health and Human Services website has health information related to women, including prenatal test recommendations.