Understanding Ultrasound

Women's Health |

Ultrasound is without a doubt the most important innovation in obstetrics in the last 50 years. Before ultrasound, we relied on our hands to feel the mother’s abdomen, a tape measure to check the size, and a stethoscope to hear the fetal heartbeat to determine whether the baby was OK.

Using very high-frequency sound waves to create an image of the baby’s internal organs, ultrasound is used to learn about the health and well-being of the fetus. It is non-invasive and studies over the past 25 years have been unable to show any dangers to prenatal ultrasound when used at the recommended intensity.

Common indications for ultrasound include:
Dating the pregnancy — If you are uncertain about when you got pregnant, you should have an ultrasound as early as possible in the pregnancy.

Growth of the fetus — If your belly feels too big or too small, the fetus will be measured to determine whether he is the right size for his gestational age.

Location of the placenta

Examining the organs and their structure — a trained sonologist (doctor who specializes in obstetrical ultrasound) can diagnose structural abnormalities in utero such as cleft lip and spina bifida.

Development of the circulation supporting the baby — to learn whether the heart and placenta are working as they should

It’s fun to see your baby before she’s born and parents-to-be like to have that first baby picture, but do you really need an ultrasound? The official policy of the American College of Obstetrics and Gynecology is that ultrasound is not a required part of routine prenatal care. That said, some studies show that 75 percent of pregnant women have an indication for ultrasound, like a family history of birth defects or an abnormal triple screen.

I, for one, cannot imagine my wife not having an ultrasound during her pregnancies. Where I practice, most insurance companies pay for one ultrasound during the pregnancy. If you’re going to have only one, I recommend having it done between 16 and 20 weeks’ gestation (as measured from the last menstrual period). At that point, the fetus is developed enough to see the anatomy clearly and small enough to confirm dates accurately.

All ultrasounds, or scans, are not the same. Have yours done by the most experienced team you can find. Studies show that busy medical centers that do a lot of scans have a better track record of diagnosing anomalies than places that do only a few.

In many practices a sonographer will make the image and a sonologist will interpret it. In others the physician sonologist does the scan. I recommend asking if the practice where your scan is being performed is accredited either by the American Institute of Ultrasound in Medicine or the American College of Radiology. If there is any question about the baby’s development or structures, ask for a referral to a specialist who is familiar with abnormal fetal sonograms.

Most babies are normal, so don’t worry. Watching your baby move, and learning that she is healthy is a great comfort to many parents and even starts the bonding process before birth. Enjoy your scan!