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Ultrasound Scan during Pregnancy

What is ultrasound scanning?

An ultrasound scan is a safe and painless procedure done to look at the organs inside the body. It uses high-frequency sound waves and their echoes to create video pictures of the organs and tissues in your body.

When is it used in pregnancy?

Your healthcare provider uses ultrasound to look at:

  • Your baby
  • The placenta, which is the tissue inside the uterus that carries oxygen and food from your blood through the umbilical cord to your baby’s blood
  • The fluid around your baby
  • Your uterus, ovaries, and cervix (the opening to the uterus)

You may have 1 or more ultrasound scans as part of your routine care during pregnancy. An ultrasound scan may be done for different reasons at different stages of the pregnancy. For example:

  • Ultrasound exams in the first or early second trimester (before 16 weeks) are used to:
    • Check the age, size, weight, and position of your baby
    • Help decide your due date and check for more than 1 baby
    • Make sure your baby is growing in your uterus and not outside the uterus (ectopic pregnancy)
    • See if the placenta is normal
  • Exams between 18 and 22 weeks are often used to check your baby for any signs of a genetic problem or birth defect.
  • Ultrasound scanning may be done closer to the end of a pregnancy to:
    • Check your baby’s breathing, movements, heart rate, and muscle tone
    • Help with other tests or procedures
    • Check the amount of fluid around your baby inside your uterus
    • Look for the cause of vaginal bleeding or pelvic pain

Sometimes an ultrasound can tell whether your baby is a boy or a girl after 16 weeks of pregnancy. However, this is not the main reason for doing an ultrasound.

How do I prepare for this procedure?

In general, you do not need to do anything special to prepare for the scan. Some scans, such as an ultrasound of the uterus, require a full bladder. If you are having an ultrasound scan that requires preparation, your healthcare provider will give you instructions.

What happens during the procedure?

The ultrasound scan may be done at your healthcare provider's office, a clinic or hospital, or a radiology center.

A small device is placed on your belly. A gel is put on your skin to improve the contact between your belly and the device. If the scan is done from inside the vagina, a device shaped like a narrow tube is used and inserted gently into the vagina. The device is connected to a computer with a display screen. High-frequency sound waves pass from the device through your body. You cannot hear the sound waves. As the sound waves pass through your body, they bounce off the organs and tissue to show pictures of your uterus, the baby, and the tissue and fluid that surrounds and protects your baby.

Generally an ultrasound scan is done in 20 to 30 minutes. A vaginal ultrasound usually takes less than 5 minutes.

What happens after the procedure?

Usually you can go home and go back to your normal activities as soon as the scan is done. You may get the results of the ultrasound within a few minutes to a few days later.

What are the risks of this procedure?

Ultrasound has no known risks because the sound waves are not dangerous.

Developed by RelayHealth.
Adult Advisor 2015.1 published by RelayHealth.
Last modified: 2014-09-22
Last reviewed: 2014-09-21
This content is reviewed periodically and is subject to change as new health information becomes available. The information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional.
Copyright ©1986-2015 McKesson Corporation and/or one of its subsidiaries. All rights reserved.
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