A pregnancy ultrasound is an imaging test that uses sound waves to see how a baby is developing in the womb. It is also used to check the female pelvic organs during pregnancy.

Pregnancy sonogram; Obstetric ultrasonography; Obstetric sonogram; Ultrasound - pregnancy

You will lie down for the procedure. The person performing the test places a clear, water-based gel on your belly and pelvis area and then moves a hand-held probe over the area. The gel helps the probe transmit sound waves. These waves bounce off the body structures, including the developing baby, to create a picture on the ultrasound machine.

In some cases, a pregnancy ultrasound may be done by placing the probe into the vagina. For information on this procedure, see transvaginal ultrasound.

A full bladder is necessary to get a good picture. Therefore, you may be asked to drink 2 to 3 glasses of liquid an hour before the test. You should not urinate before the procedure.

There may be some discomfort from pressure on the full bladder. The conducting gel may feel slightly cold and wet. You will not feel the ultrasound waves.

Some doctors order an ultrasound when they think there may be a problem with the pregnancy or if there is a question about how far along the pregnancy is. Others advocate screening ultrasounds. You should consult your health care provider to determine the most appropriate scanning schedule for you.

A pregnancy ultrasound may be done in the first trimester to:

• Confirm a normal pregnancy
• Determine the baby's age
• Look for problems, such as ectopic pregnancies or the chances for a miscarriage
• Determine the baby's heart rate
• Look for multiple pregnancies (twins, triplets, etc.)
• Identify problems of the placenta, uterus, cervix, and ovaries

A pregnancy ultrasound may also be done in the second and third trimesters to:

• Determine the baby's age, growth, position, and sometimes gender
• Identify any developmental problems
• Look for multiple pregnancies (twins, triplets, etc.)
• Look at the placenta, amniotic fluid, and pelvis

Some centers are now performing a pregnancy ultrasound around 9 - 13 weeks of pregnancy to look for signs of Down syndrome or other developmental problems in the developing baby. This test is often combined with blood tests to improve the accuracy of results.

The total number of scans will depend on whether a previous scan or blood test has detected problems that require follow-up testing.

Images

Ultrasound in pregnancy

Ultrasound, normal placenta - Braxton Hicks

Ultrasound, normal fetus - foot

Ultrasound, normal fetus - heartbeat

Ultrasound, normal fetus - femur measurement

Ultrasound

Ultrasound, color - normal umbilical cord

Ultrasound, normal fetus - profile view

Ultrasound, normal fetus - arms and legs

Ultrasound, normal fetus - heartbeat

Ultrasound, normal relaxed placenta

Ultrasound, normal fetus - face

Ultrasound, normal fetus - spine and ribs

Ultrasound, normal fetus - head measurements

Ultrasound, normal fetus - arm and legs

Ultrasound, normal fetus - ventricles of brain

Ultrasound, normal fetus - abdomen measurements

Review Date: 02/21/2010
Reviewed By: Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington, School of Medicine; Susan Storck, MD, FACOG, Chief, Eastside Department of Obstetrics and Gynecology, Group Health Cooperative of Puget Sound, Redmond, Washington; Clinical Teaching Faculty, Department of Obstetrics and Gynecology, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org)