Ultrasound Exams

An ultrasound exam makes an image of your baby from sound waves. These sound waves are produced by a device called a transducer. The transducer is either moved across your abdomen, which is called a transabdominal ultrasound scan, or placed in your vagina, which is called a transvaginal ultrasound scan. The method chosen depends on what needs to be seen and the gestational age. A first-trimester ultrasound is used to:

• Confirm the pregnancy by locating the amniotic sac in which the baby is developing
• Estimate the gestational age
• Determine whether the baby’s heart is beating
• Check whether there is more than one baby
• Screen for birth defects
• Examine the uterus and ovaries

Most women have a second-trimester ultrasound that is usually performed after 18 weeks of pregnancy. It is used to check the baby’s anatomy, heart function and position. The level of amniotic fluid is checked, and sometimes it is possible to determine the baby’s sex. A detailed ultrasound exam may be recommended if the health care provider suspects a possible problem based on the medical history or the results of other tests.

During an ultrasound exam, sound waves are produced by a transducer. These sound waves are reflected off the fetus and changed into pictures that you and your health care provider can view on a screen.