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Five Things You May Not Know About Ultrasound 

1. Ultrasound images are based on sound.

A prenatal ultrasound uses high frequency sound waves that are undetectable to the human ear. The echoes of these sound waves are recorded and transferred into images of your baby. The gel on your belly helps provide a better image for the doctors to see your baby.

2. Doctors are looking at more than just your baby.

The fetal ultrasound gives doctors a picture of the health of the mother and baby. It provides images of the baby, the umbilical cord, the placenta, and amniotic fluid. During a first trimester ultrasound doctors can tell if you are pregnant with more than one baby, and if you baby has birth anomalies that may affect the brain or spinal cord. A second trimester ultrasound provides insight on the position of the fetus and placenta, and can show major birth anomalies such as a neural tube or heart defect, or missing kidneys. A third trimester ultrasound shows the size and position of the baby and the placenta. This information helps doctors prepare for the delivery of your baby.

3. The ultrasound technician will take a series of measurements.

The measurements of your baby are compared to normal measurement of babies of similar age. These numbers help doctors determine the growth of your baby, the gestational age, and can indicate certain birth anomalies. Some of the measurements taken include:

  • Crown-rump length (CRL)
    • This is the length between the top of the embryo and it’s bottom. This measurement is typically used to judge the age of your baby.
  • Biparietal Diameter (BPD)
    • The BPD is the diameter between the two sides of the head.
  • Femur Length (FL)
    • The FL measures the longest bone in the body. It helps doctors determine the growth length in your baby.
  • Abdominal Circumference (AC)
    • The AC measurement helps doctors determine the size and estimated weight of your baby.

4. The ultrasounds technician will not talk with you about your ultrasound images.

Every baby and every situation is different. It is important for the ultrasound technician to discuss the images and measurements with the doctor before providing a diagnosis.

5. An ultrasound can take more than an hour to complete.

Sometimes your little one may not want to have a photo taken. You baby needs to be in the correct position for the ultrasound technician to gather the proper measurements and images. This, combined with the amount of information that needs to be gathered to provide a full clinical picture of your baby’s well-being can take anywhere from 30 minutes to an hour or more.

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