Obstetric Ultrasound
Obstetric Ultrasound
Obstetric ultrasound uses sound waves to produce pictures of a baby (embryo or fetus) within a pregnant woman, as well as the mother’s uterus and ovaries. It does not use ionizing radiation, has no known harmful effects, and is the preferred method for monitoring pregnant women and their unborn babies. A Doppler ultrasound study – a technique that evaluates blood flow in the umbilical cord, fetus or placenta – may be part of this exam.
This procedure requires no special preparation. Since only your lower abdominal area needs to be exposed for this exam, you may want to wear a loose-fitting, two-piece outfit.

What is Obstetrical Ultrasound Imaging?
Ultrasound imaging is a noninvasive medical test that helps physicians diagnose and treat medical conditions. It is safe and painless. It produces pictures of the inside of the body using sound waves. Ultrasound imaging is also called sonography. It uses a small probe called a transducer and gel placed directly on the skin. High-frequency sound waves travel from the probe through the gel into the body. The probe collects the sounds that bounce back. A computer uses those sound waves to create an image. Ultrasound exams do not use radiation (x-rays). Because ultrasound captures images in real-time, it can show the structure and movement of the body’s internal organs. The images can also show blood flowing through blood vessels.
Obstetrical ultrasound provides pictures of an embryo or fetus within a woman’s uterus, as well as the mother’s uterus and ovaries.
What are some common uses of the procedure?
Obstetrical ultrasound is a useful clinical test to:
- establish the presence of a living embryo/fetus
- estimate the age of the pregnancy
- diagnose congenital abnormalities of the fetus
- evaluate the position of the fetus
- evaluate the position of the placenta
- determine if there are multiple pregnancies
- determine the amount of amniotic fluid around the baby
- check for opening or shortening of the cervix
- assess fetal growth
- assess fetal well-being
How should I prepare?
You should wear a loose-fitting, two-piece outfit for the examination. Only the lower abdominal area needs to be exposed during this procedure.
The radiologist or sonographer may elect to examine an early pregnancy by means of transvaginal ultrasound in order to see the pregnancy more closely or to assess the cervix. For more information on transvaginal ultrasound, see the Pelvic Ultrasound page.