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What to expect at your 20-week ultrasound appointment

The anatomy scan is about more than just finding out your baby’s sex. Learn what happens at your 20-week ultrasound appointment.

What to expect at your 20-week ultrasound appointment


The 20-week ultrasound, an anatomy scan that takes place between 18 and 22 weeks is probably one of the longest and most detailed ultrasounds you’ll have during your pregnancy. We asked the experts how to prepare and what to expect.

How long does the 20-week ultrasound take?

Be prepared to spend at least an hour at your 20-week ultrasound appointment, not to mention the time you’ll spend in the waiting room. Your actual scan will probably take about 45 minutes to an hour, or even up to 75 minutes if you are considered high-risk, explains Susan Kinnear, manager of diagnostic imagingat Hamilton Health Sciences Centre and director at large for Sonography Canada. Don’t be afraid to tell the sonographer if you’re uncomfortable, she says, as many women think they have to just bear it if their back hurts or they need to move or go to the bathroom. After the ultrasound, the sonographer has to write up the case, so you may have to wait afterwards as well if you are seeing your doctor for a follow-up appointment or if there are any concerns.

What happens at the 20-week ultrasound?

A sonographer will put gel on your belly and use a transducer (ultrasound wand) to get ultrasound images, which are high-frequency sound waves that create images of what’s happening inside your body. You may be asked to move from side to side to get the best images.

 What do you need to prepare for the anatomy ultrasound?

You don’t need to load up on water for the 20-week ultrasound (after 12 weeks you’re good!), but you should eat a meal or snack beforehand because, as mentioned, this is a long one. Eating may also make the baby more active so that the sonographer can see different angles.

What is the sonographer looking for at the 20-week ultrasound?

This scan involves taking ultrasound images and measurements of the baby’s face, brain, spine, heart, kidneys, diaphragm, chest, stomach, bladder, genitals, limbs, feet and hands, as well as the umbilical cord.The sonographer will also measure the size of the fetus, look at the location of the placenta and measure the level of amniotic fluid, explains Doug Wilson, a professor of obstetrics and gynecology at the University of Calgary in Alberta. They will check the baby’s heart rate, as well as your cervix to make sure that it’s clear of the placenta, closed and long, says Kinnear. (Cervical length is important, as a shortened cervix can increase your risk of preterm labour. It can also begin to open too early, which a technician will check for.)

What abnormalities can be detected at the 20-week ultrasound?

In this detailed scan, the sonographer will look at the baby’s overall anatomy to flag any abnormalities, such as a heart defect or opening in the spine. “You can’t tell the baby’s health, but you can tell the anatomical structures and if they look like they’re in a normal place,” says Wilson. For example, the scan can identify if there is fluid in the bladder, which means that the kidneys are working, or if the heart chamber looks like it’s functioning properly.


At the 20-week ultrasound, the sonographer may also be looking for markers for genetic disorders, such as Down syndrome and trisomy 18. (If you opted for prenatal screening in your first trimester, this bloodwork, in combination with an 11- to 14-week ultrasound scan, will have already given you information on your risk for certain genetic disorders, explains Wilson.) Now that your baby is much bigger, this scan could provide additional information on your baby’s growth and any abnormalities.

Will you find out the sex of the baby?

The 20-week ultrasound is often known as the “gender reveal,” but it depends on the baby’s position and the medical directive from the clinic or hospital where you have the scan. A sonographer needs to get a clear image of the genitals to tell whether it’s a boy or girl, and there’s always a small chance that it could be wrong. For a female fetus, they are looking for the vulva, clitoris and labia; for a male fetus, they are looking for the scrotum, testicles, penile midline rapheand penis.While you can be fairly sure that the gender is accurate, they can misidentify the baby or may not see it clearlyto tell you. (You can also find out the gender if you do noninvasive prenatal testing, or NIPT, as they screen for sex-related chromosomal disorders.)

What does your baby look like at 20 weeks pregnant?

At about halfway through your pregnancy (or 20 weeks), your baby is about the size of a banana (or about 10 ounces). The limbs, face, neck, spine and heart are formed, so they finally look like an actual baby, not just a tiny spot on the ultrasound.

Should you bring someone with you?

Generally, you’ll be allowed to bring someone in the room with you, and it’s usually best to have them there for this 20-week scan, recommends Kinnear. But don’t bring your entire family because they won’t be allowed in the room. “There’s a lot of work that goes into getting the right images,” says Kinnear. “If they want to do a really good job, they have to concentrate.” Depending on the clinic, if your family comes for the “gender reveal,” they may be able to come in for the last 10 minutes, says Kinnear.

How many ultrasounds will you have during pregnancy?

If the baby is in the wrong position or won’t move enough for the sonographerto see all of their body parts properly, you might be asked to return in two weeks for another anatomical scan, explains Kinnear. If things look OK, you may not have another ultrasound before birth, unless your doctor indicates that it’s necessary.

What will the sonographer tell you?


Generally, the ultrasound sonographer isn’t supposed to tell you what they see—that’s news you’ll receive in a follow-up appointment with your doctor, says Wilson—but most technicians are allowed to tell you the gender. Also, no news is often good news. “If you’re sent away with no information, you can assume that things look good,” says Wilson.

Read more:
How many ultrasounds do you get in a typical pregnancy?
12 adorable baby shower invitations

This article was originally published on Oct 28, 2019

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Kate is an award-winning journalist and communications professional based in Toronto, Ontario. She successfully leads high-level editorial content, executes brand strategies and creates compelling content tailored to specific audiences. More of her work can be found in publications like The Toronto Star, Reader's Digest (U.S.) and Chatelaine