What Is a Fetal Ultrasound?

Fetal ultrasound, also known as prenatal ultrasound, is using ultrasound imaging technology to see the fetus in the uterus during pregnancy. Sound waves pass through the abdomen to produce an image of your growing baby on a monitor.1

There are seven kinds of ultrasound tests—two of which are the most common. The most common ultrasounds are: 1 ,2

The other kinds of ultrasounds include:

  • Standard ultrasounds.This is what most people think of when they imagine prenatal ultrasound. The transducer—the tool that emits the high-frequency sound waves that produce the image of the fetus—is applied to the abdomen to produce a two-dimensional image on a screen.

  • Transvaginal ultrasounds.Instead of viewing the fetus through the abdomen, the transducer is in a specialized wand that is inserted into the vagina. This kind of ultrasound is typically used in the early stages of pregnancy.

  • Advanced ultrasounds.Like a standard ultrasound, the transducer is applied to the abdomen to create a picture of the fetus, but other tools may be used as well. These ultrasounds are done to view a specific area of concern.

  • Doppler ultrasounds. These ultrasounds use the doppler effect to measure changes in the sound waves to measure moving objects—good for learning information about baby’s blood flow.

  • 3D ultrasounds.These specialized ultrasounds used specific probes to generate a 3D image expressed on a 2D screen.

  • 4D or dynamic 3D ultrasounds. These ultrasounds are designed to view the face and movement of the baby before delivery.

  • Fetal Echocardiography. This kind of ultrasound is used to get a detailed image of the fetus’s heart to assess function and health and rule out any defects.

What Is the Purpose of an Ultrasound?

The reasons for a prenatal ultrasound test depend on when it’s done:1

  • First trimester: An ultrasound in the first trimester is done to evaluate the placement, size, and gestational age of the fetus—or fetuses, since this is also how a doctor determines if a woman is pregnant with multiples. Examining the health of the cervix and uterus will also happen, along with potential genetic screening of the fetus.

  • Second trimester: The second trimester is when ultrasound is used to examine fetal anatomy and to learn the sex of the fetus.

  • Third trimester: There are fewer reasons to have an ultrasound in the third trimester, but your doctor may schedule one if there’s a specific concern that needs to be evaluated.

What Is a Sonogram?

A sonogram is the image an ultrasound produces.3 That’s it! And that’s precisely why these terms are used interchangeably—sometimes with a bit of confusion. Just remember: the ultrasound is the procedure; the sonogram is the visual result.

What Happens During an Ultrasound?

The process of an ultrasound typically includes:2

  • In the case of a typical transabdominal ultrasound, gel is applied to the belly while the pregnant woman lies on an examination table.

  • The sonographer moves a smooth transducer wand across the woman’s stomach to produce an image on the ultrasound monitor.

  • The technician may as the woman to turn or adjust so they can get a better view of the fetus.

  • Sometimes if they cannot get a good view of the fetus, they may need to insert a wand into the vagina and perform a transvaginal ultrasound.

An ultrasound may take between 30 minutes and an hour to complete, and typically ends with a printed copy of the sonogram image.

Getting ultrasounds are a normal part of having a healthy pregnancy for you and baby. And having a printed copy of your sonogram is a lovely keepsake—and you could have it double as your pregnancy announcement photo!