Your first ultrasound and sonogram

If you are a fan of FRIENDS like I am, you probably remember a classic scene between Ross and Rachel (No, not the “we were on a break!”) when Rachel sees her baby for the first time on ultrasound, but can’t seem to “find it.”

After much guidance from Ross, and not “embarrassing herself” in front of her doctor, she found the the “little peanut.” Click the video below for a recap.

• So what were they seeing on the ultrasound?
• What are all the wavy black lines that my doctor is analyzing on ultrasound at my first visit?
• Can I tell if it is a boy or girl?

To help determine the viability of your pregnancy, a Transvagainal ultrasound is performed because it gives your doctor the clearest and most accurate method for examining the pregnancy. Below are some images that you may see in the early stages of pregnancy. A normal pregnancy is identified with three findings!

A. The Fetal pole

B. The Yolk Sac

C. The Gestational Sac

(see the glossary for more details)

Each of these develop very early in the pregnancy, within 6 weeks of pregnancy. The Gestational Sac is a fluid filled cavity that surrounds the early developing embryo. The Yolk Sac provides early nourishment before the placenta takes over. And the fetal pole is the early stages of fetal development. By the 6-7th week, we should see a heart beat!

But why does this all matter??

As OBGYNs, this allows us to get an estimate due date. We WANT accurate due dates. We estimate your due date by comparing the first day of your last period to the length of the baby, called the crown rump length.

In my previous blog I discussed how knowing your menstrual cycle and its timing is critical. By comparing the dates with the size of the fetus, we can get a more accurate picture of the time of conception.

Lastly, this particular ultrasound can’t determine the sex of the baby. An official sonogram at 18-20 weeks of pregnancy will look at the anatomy of the fetus. There are, however, new blood tests that primarily evaluate the fetal risk for down syndrome (and the like), as well as determine the sex of the baby. This blood test is usually done ideally at 9-10 weeks of pregnancy.

Thats really it for the first ultrasound. You are ready to explain it to someone else! And if you still “can’t see it,” feel free to ask me questions. Place comments below or on my instagram page! And make sure to consult your own physicians if you have more questions or concerns.

Glossary of Terms:

Gestational Sac – fluid filled cavity that surrounds the early developing embryo (the yolk sac and fetal bowl). This is seen at 4-5 weeks of pregnancy.

Yolk Sac – provides early nourishment before the placenta takes over. Seen at 5-6 weeks

Fetal Pole – The early stages of fetal development, seen at 5.5-6.5 weeks

Crown Rump Length – This is used calculating gestational age. With this gestational age, doctors can estimate your potential due date. The earlier the first ultrasound is performed, the more accurate the baby’s gestational age will be.