What are the two main types of pregnancy ultrasounds?
The two main types of pregnancy ultrasound are transvaginal ultrasound and abdominal ultrasound. Both use the same technology to produce images of your baby. Your pregnancy care provider performs a transvaginal ultrasound by placing a wand-like device inside your vagina. They perform an abdominal ultrasound by placing a device on the skin of your belly.
Transvaginal ultrasound
During a transvaginal ultrasound, your pregnancy care provider places a device inside your vaginal canal (similar to how you place a tampon). In early pregnancy, this ultrasound helps to detect a fetal heartbeat or determine how far along you are in your pregnancy (gestational age). Images from a transvaginal ultrasound are clearer in early pregnancy as compared to abdominal ultrasound.
Abdominal ultrasound
Your pregnancy care provider performs an abdominal ultrasound by placing a transducer directly on your skin. Then, they move the transducer around your belly (abdomen) to capture images of your baby. Sometimes slight pressure has to be applied to get the best views. Providers use abdominal ultrasounds after about 12 weeks of pregnancy.
Traditional ultrasounds are 2D. More advanced technologies like 3D or 4D ultrasound can create better images. This is helpful when your provider needs to see your baby’s face or organs in greater detail. Not all providers have 3D or 4D ultrasound equipment or specialized training to conduct this type of ultrasound.
Your provider may recommend other types of ultrasounds. Examples of additional ultrasounds are:
- Doppler ultrasound: This type of ultrasound checks how your baby’s blood flows through its blood vessels. Most Doppler ultrasounds occur later in pregnancy.
- Fetal echocardiogram: This type of ultrasound looks at your baby’s heart size, shape, function and structure. Your provider may use it if they suspect your baby has a congenital heart condition, if you had another child that had a heart condition or if you have certain health conditions that warrant taking a closer look at the heart.
How do I prepare for the test?
There’s no special preparation for an ultrasound. Some pregnancy care providers ask that you come with a full bladder and don’t use the restroom before the test. This helps them view your baby better on the ultrasound. You can bring a support person, but bringing children is discouraged as this is an important test that requires complete focus.
You may be asked to change into a hospital gown, but this isn’t usually required for abdominal ultrasounds. If your provider is performing a transvaginal ultrasound in your first trimester, you’ll put on a hospital gown or undress from the waist down.
What should I expect during a prenatal ultrasound?
You’ll lie on a padded examining table during the test. Most ultrasounds occur in a dimly lit room, which helps your ultrasound technician (or sonographer) see the screen. Your sonographer applies a small amount of water-soluble gel to the skin of your belly. The gel doesn’t harm your skin or stain your clothes, but it may feel cold. This gel helps transmit sound waves more efficiently.
Next, the sonographer places a transducer on the skin of your abdomen. The transducer sends sound waves into your body, which reflect off internal structures, including your baby. The sound waves that reflect back create pictures on a screen. Your sonographer uses these images to take important measurements such as your baby’s head circumference and length. You may see them making lines on the screen or clicking a button to “freeze” certain angles.
There’s virtually no discomfort during a prenatal ultrasound. You may feel mild discomfort if you have to pee. The ultrasound test takes about 30 minutes to complete.
If you have a transvaginal ultrasound, the process is only different in that the transducer is inside your vagina and not on your belly.
What should I expect after a pregnancy ultrasound?
If you had an abdominal ultrasound, your sonographer wipes the gel off your belly. They may print off some ultrasound pictures for you to take home with you.
In most cases, your sonographer won’t discuss the results of your test with you. If your obstetrician performs your ultrasound, they may discuss what they see as they go along.
If a sonographer performs your ultrasound, an obstetrician will look at the images, then discuss their findings with you at your next appointment. Most practices schedule your appointment right after your ultrasound so you get your results the same day.
What are the risks of prenatal ultrasounds?
Studies have shown ultrasounds are safe during pregnancy. There are no harmful side effects to you or your baby.
Is it safe to do an ultrasound every month during pregnancy?
While ultrasounds are safe for you and your baby, most major medical associations recommend that pregnancy care providers should only do ultrasounds when the tests are medically necessary. If your ultrasounds are normal and your pregnancy is uncomplicated or low risk, repeat ultrasounds aren’t necessary.
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