Obstetrical ultrasound uses sound waves to produce images of a developing baby inside its mother, as well as images of the mother's uterus and ovaries. These images are captured in real-time, so they can reveal the structure and movement of the fetus and beating heart.
Because ultrasound does not use radiation and has no known harmful effects, it 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 also be part of this exam.
Emerson Hospital’s expert sonographers perform obstetrical ultrasound at the main Emerson campus in Concord and at Emerson’s Westford Health Center
In addition, Emerson Hospital provides a high-risk obstetrics clinic
with genetic counseling should any fetal problems be discovered.
Why obstetrical ultrasound is performed
Obstetrical ultrasound is an important clinical test that can yield vital information about the health of a developing fetus. It can:
- Establish the presence of a living embryo/fetus
- Assess fetal growth and well-being
- Estimate how far along a pregnancy is
- Determine if there are multiple pregnancies
- Diagnose congenital abnormalities in the fetus
- Evaluate the position of the fetus
- Determine the amount of amniotic fluid around the baby
What obstetrical ultrasound involves
You should wear a loose-fitting, two-piece outfit for this exam. Only your lower abdominal area needs to be exposed during the procedure.
If your ultrasound is scheduled early in your pregnancy (during the first trimester), you will need to finish drinking 24 ounces of fluid (water, juice, coffee or tea) one hour prior to your exam (a full bladder is needed for the procedure). Air interferes with sound waves, so if your bladder is distended, it pushes the air-filled bowel out of the way so we can obtain an image of the uterus and embryo or fetus.
During your exam, a specially-trained Emerson sonographer will press a small hand-held transducer against your skin and move it over your abdomen. A small amount of gel will first be applied to help eliminate air pockets between your skin and the device.
The radiologist or sonographer may want to examine an early pregnancy using transvaginal ultrasound. For this exam, the transducer is attached to a probe and inserted into the vagina to view the uterus and ovaries. This exam requires an empty bladder. You will be given specific instructions for this imaging study when you make your appointment.
With either technique, the transducer sends information to a computer, which produces detailed images based on the patterns created by the sound waves.
An ultrasound exam is generally a painless procedure, and a typical exam takes from 30 minutes to an hour. You are free to resume all normal activities after your test.