Boy or Girl Ultrasound Wrong? Gender Scan Accuracy 4

Already being the mom of two little boys, I was admittedly a bit disappointed at my 16 week ultrasound with my third child when the tech said she thought it was a boy. I was thrilled, of course, he was healthy, but still deep down was hoping for a girl. Looking at my ultrasound photo, which you can see below:

boy or girl ultrasound wrong gender scan accuracy

Boy ultrasound 16 weeks

I would agree, my baby looked like a boy. I, however, did note he didn’t look quite like the ultrasound photos from about the same time period on my other two sons, so I started doubting gender scan accuracy and wondering if ultrasounds can be wrong. After looking to the internet for answers, it turns out that early ultrasound photos are often mistaken. Incorrect guesses of male more often than female even. In the end, my baby was actually a boy, but here’s hope for all those who are hoping for a verdict of “ultrasound wrong.”

Boy Ultrasound Wrong: How in the heck could a girl look like a boy?

There are two reasons early ultrasound photos can make a girl look like a boy. The first is simple. The ultrasound tech or doctor sees an umbilical cord between the legs and mistakes it for manhood. This can actually happen at any gestational age, making a clear image pretty important if you plan to buy non-neutral gender baby goods.

Second, many parents are aware that all babies start off appearing as the same sex, the misconception is that all babies begin female, so if there is a dangly thing between the legs, you have a boy. This isn’t the case. During the early weeks of external gender development both male and female fetuses have a dangly part down there as well as a bulbous area. You can see a clear visual aid and explanation here. Somewhere between 9 and 12 weeks the “dangly” part in the center forms the clitoris of a girl or the penis of a boy, and the bulbous area becomes either a scrotum or labia. This means a say, 11-week shot with a clear sack-like shape and tiny dot in the middle that looks a little like the “turtle head” image said to indicate a boy could still been a girl in development. It’s because of this that gender scan accuracy is greater after the 20th week when, in the majority of babies that have been accurately aged, external sex organ development is complete and the baby is larger.

Girl Ultrasound Wrong: Can a girl turn out to be a boy then?

gender ultrasound accuracy

characteristic 3 line girl ultrasound at 17 weeks

It’s less common to be told your baby is a girl based on a gender scan and actually end up with a boy, but it does happen. For example, if the image isn’t very clear or from a bad angle there may not appear to be male genitalia even if there is. Inexperienced techs often assume no penis means a girl. For a confirmed girl ultrasound typically you want to see 3 lines, indicating the shape of a vagina. Again, this is why 3D ultrasound is generally more accurate in predicating gender.

Can you tell if a baby is a girl or boy by ultrasound before the 20 week mark?

You can’t get much more than a guess, a solid guess if you are approaching 20 weeks. In all four of my pregnancies, gender was very clear by 16-17 weeks. There is also the angle of the dangle theory. Between 12 and 15 weeks when looking at a side view on the ultrasound if the dangly middle part is at a 30 degree angle or greater with the spine, your baby is likely a boy, and if it’s 30 degrees or under, then you likely have a girl. The 30 degree on the dot mark leaves you still without hints. Basically, is the dangle pointing more up towards your baby’s head (boy), or down at the toes (girl)? Either way this guess is still only about 50% accurate. With these early scans normal Doppler ultrasounds are recommended, while later, after the 20th week, 3D ultrasounds are generally more accurate.

If you are experiencing a bit of gender disappointment, have faith, we confirmed our fourth child was a girl by ultrasound October 9, 2014.

You might also like:
Baby Gender Prediction Quiz based on the science of gender swaying

Can Pregnancy Symptoms Predict Gender?

How Gender is Determined

External Gender Development

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4 thoughts on “Boy or Girl Ultrasound Wrong? Gender Scan Accuracy

  • gugu

    Actually, it’s the other way round. It’s more often to mistake a boy as a girl because all babies start off as girls. So no dangling thing, oh, it’s a girl. Then it turns out to be a boy.
    Mistaking a girl to be a boyis less likely because you actually need the tangible proof of a male genitalia to make the conclusion that it’s a boy.

  • curiousmom

    Hey, just got my US done. Every image is so different. One looks a little similar to the image which shows “Girl Ultrasound Wrong: Can A Girl Turn Out To Be A Boy Then?” . It says its a girl. So its girl, or boy?

    • unwirklich admin

      The image tags on both pics are the same I think, those are just for search engines to know what the page is about. The top pic is a boy around 16 weeks the bottom a girl. The captions should reflect this 🙂 If you are past 16 weeks or so, and seeing sort of a turtle head like bulge, probably boy, if you are seeing 3 lines no or very little bump, girl.