An ultrasound is a high frequency sound, higher than people can hear. During an ultrasound, a small hand-held device called a transducer sends high frequency sound waves into the body and identifies their echoes as they bounce off internal structures. This information is then translated by a computer and images of the baby are generated onto a computer monitor.

Who usually performs the ultrasound examination?

The ultrasound is performed by a diagnostic medical sonographer, a health care professional who is specially-trained to perform ultrasound. The sonographer reviews the images as well as the patient’s history with a physician trained to interpret ultrasound. The physician will discuss the results with you.

How long does an ultrasound exam take?

A complete obstetric ultrasound usually takes between 30 to 60 minutes.

What happens during the ultrasound?

During a transabdominal ultrasound, the sonographer places some clear gel on your lower abdomen and then presses the transducer against your skin. The gel makes it possible for the sound waves to travel into your body. The sonographer moves the transducer across your abdomen to view different areas of your body and your baby. This exam is generally painless. It is helpful if your bladder is at least partially full, so please do not urinate immediately before the exam.

A transvaginal ultrasound allows your physician to get a closer look at your baby. During a transvaginal ultrasound, the sonographer inserts a special transducer into your vagina. The transducer is about the size of a tampon and is smaller than a speculum (used during a Pap test). There may be some pressure from this ultrasound, but it should not hurt. This exam does not affect your pregnancy. You should empty your bladder before the exam.

Is ultrasound safe?

Widespread research in diagnostic ultrasound has not revealed any harmful effects.

What an ultrasound can do:

• Help determine the length of the pregnancy (dates) and the estimated due date*
• Evaluate a threatened miscarriage
• Evaluate the baby’s well being such as development and anatomy including sex, growth, fluid around the baby and location of the placenta
• Check on babies in a multiple pregnancy
• Check on the baby in a high risk pregnancy
• Check on pre-term changes in the cervix
• Identify problems with the uterus or ovaries

*A full-term pregnancy can last anywhere from 37 to 42 weeks. Your actual delivery date could be different from your estimated due date. A very small percentage of babies are born on their estimated due date.