For What to Expect’s "What I Wish I’d Known" series, moms and dads share the wisdom they’ve gained since first becoming parents. 

During my first pregnancy, one appointment loomed large in my mind: the infamous 20-week anatomy scan. There’s a lot riding on this routine ultrasound, which typically happens between 18 and 22 weeks of pregnancy. It’s when providers check your baby’s growth, organs, skeleton, amniotic fluid, placenta, cervix, and umbilical cord. You can also learn the baby’s sex if you haven’t already, through early bloodwork. It’s comprehensive, an important milestone, and I felt very nervous as I approached the appointment date. 

“The anatomy scan detects approximately 50% of major structural malformations,” notes Shannon Smith, M.D., an OB/GYN at Brigham Faulkner OB/GYN Associates in Boston and a member of the What to Expect Medical Review Board. “When abnormalities are identified, this enables timely genetic counseling, diagnostic testing, subspecialist consultation, delivery planning at appropriate facilities, and informed decision-making regarding pregnancy management.”

In other words, yes, this can be an appointment when serious issues are discovered. But it’s also an appointment where you get to see a detailed view of your baby, which can be informative, reassuring and even joyful. My baby was perfectly healthy, and by my second pregnancy, I walked into this scan calm and confident. Here’s what I wish I’d known going into my first anatomy scan appointment. 

It can be an emotional experience 

I was not alone in feeling the feels about the 20-week anatomy scan. “My scan is Friday, and I’m honestly freaking out,” one What to Expect community member shares. Doctors hear this all the time, too. Dr. Smith says the anatomy scan is often one of the most anticipated prenatal appointments. 

“It feels like a significant milestone: confirmation that everything is structurally on track as the pregnancy moves into its later stages,” she explains. “From an emotional perspective, the anatomy scan is often the first time parents see their baby in a detailed, recognizable way.” You’ll likely see clear images of the face, hands, and feet, along with your baby’s movements on the big screen. And those fun 3-D images you see on social media? This is often the appointment where you may have the option to get them.

For me, staying pretty tight-lipped about my pregnancy until after the scan helped me manage my anxiety. Once we knew everything looked on track, I felt comfortable sharing the news more widely. To calm nerves, Dr. Smith recommends telling your care team how you’re feeling, bringing a support person, and preparing questions ahead of time. Scheduling the scan earlier in the day can also help — sometimes it’s easier when you don’t have hours to overthink it.

You may need a full bladder…or not

Typically, when I showed up to OB-GYN appointments during pregnancy, I was asked to pee in a cup. Not this time.  

“Many offices will recommend coming to the exam with a full bladder, as it can help with positioning the fetus and uterus in a way that makes it easier to obtain the proper images,” explains Mohak Mhatre, M.D., a Maternal-Fetal Medicine Physician at Tufts Medical Center. “The sonographer may ask you to go to the bathroom in the middle of the exam because sometimes emptying the bladder helps change the fetal position.”

As someone with a historically small bladder — which only got worse during pregnancy — this wasn’t my favorite surprise, but it was manageable. And if you’re truly uncomfortable, speak up. Sonographers can usually adjust the exam to get you relief quickly. After I finally couldn’t take it and took a tinkle, my sonographer had me roll onto my side to complete the scan. It’s another way to access the baby’s position, Dr. Mhatre notes.  

A transvaginal ultrasound is sometimes part of it

Remember in the early days when the doctor went up in there to see the baby? Even at 20 weeks, a transvaginal ultrasound may still be needed, in addition to the abdominal one.

“While most views can be obtained abdominally, sometimes specific views of the cervix, placenta, and umbilical cord are best seen transvaginally,” says Dr. Mhatre. “Occasionally, depending on fetal position, it can also help evaluate different parts of the body.”

I remember it felt awkward, especially with a full bladder, but I managed, knowing it’s done to get the clearest, most accurate information possible.

Plan to take time off work

This is not a quick in-and-out appointment. The anatomy scan often lasts up to 90 minutes, sometimes longer if you’re carrying multiples. Block your work calendar — the last thing you want to be worried about is if you’re getting Slack messages. And if you bring a partner, make sure they’re aware of the timeline, too. 

“We cannot force the fetus to move into a better position,” Dr. Mhatre explains. “Some of them are more ‘camera shy.’” That means waiting, repositioning, rolling from side to side, and sometimes taking breaks while the sonographer captures the many required images of the heart, organs, skeleton, and more.

Wear comfortable clothes, bring a snack, stay hydrated, and don’t hesitate to ask questions or request a break. “Feel free to change positions or take breaks as needed,” adds Dr. Smith. “Sometimes movement helps the baby shift for better views, and this is a normal part of the process.”

You might feel lightheaded lying on your back

After avoiding lying on my back during prenatal workout classes and in bed at night, it was strange to be positioned on my back for such a lengthy period of time. While I was generally okay being on my back for both appointments, not all moms were. Natalie Murphy shares her experience on TikTok: “In the last 60 seconds of my ultrasound…I was like, something is not right…by the time I sat up, I was like, I do not feel well.” She describes experiencing a full-body sweat, feeling short of breath, and feeling like she was going to pass out.

“Some patients feel lightheaded while lying on their back,” Dr. Mhatre confirms. “This can happen when the uterus compresses the vena cava (the blood vessel that brings blood back to your heart).”

If you feel sweaty, dizzy, short of breath, or just off, say something right away. Sitting up, turning onto your side, drinking water, or using pillows for support often brings quick relief. “Never hesitate to tell anyone if you are not feeling well — technicians can always work around you and the baby!” advises Dr. Smith.

You could have to go back

If the fetus doesn’t cooperate during the scan, you may need a follow-up appointment to capture missing images. Roughly 13–15% of patients require a repeat scan, according to Dr. Smith. 

“I had mine yesterday,” a WTE community member shares. “Baby was doing gymnastics, so I have to go back in one week.” Another mom echoes, “It lasted a little over an hour as the tech was a student, and then the tech had to do it again. They don’t show us the screen at all till the end. After 45 minutes, she had me rolling around and jiggling to get him to show his face, and nothing. No cute profile baby pics this time. She said I will have to go back to get all the measurements.”

In these cases, the patient returns in a few weeks for a shorter ultrasound to complete the remaining views, Dr. Mhatre explains. Usually, the fetus has grown or changed positions, allowing the sonographer to complete the remaining views. This is especially important when it comes to the heart and other organs.

Being asked to return can feel disappointing, but it’s usually logistical, not diagnostic. “Being called back does not mean something is wrong,” Dr. Smith emphasizes. “It simply ensures a thorough and accurate assessment.”

The technician may not be able to tell you much

Every time the ultrasound technician moved around to get a closer look at something or asked me to change positions, it triggered me to worry, “What’s she seeing?” And even though you’re spending a lot of time with this person, they’re going to be pretty tight-lipped about what the camera is revealing. 

“Ultrasound technicians generally cannot give diagnostic results,” explains Dr. Smith. “This lack of conversation is routine and professional, not a sign that something is wrong.” 

What the sonographer can sometimes share: visible features, like hands or facial details. They can also see the fetus’s genitalia, so if you don’t want to know the sex, be upfront. Official results come from a Maternal-Fetal Medicine physician, sometimes immediately or within a few days. It’s the MFM’s job to communicate the scan’s findings and offer support, if needed.

“The waiting period can be stressful,” says Dr. Mhatre. “Acknowledge your feelings, engage in self-care, and seek support. Try to stay positive and focus on the possibility of normal results (which is most common).”

It may be cute and really fun

Okay, now that the hard stuff is out of the way, it’s worth saying: this appointment can also be a special milestone. While I was admittedly wound up before my first baby’s scan, everything went smoothly. My favorite moment was when she waved her tiny hand at us. She slept through the first part of the appointment, so I was told to drink some sugary juice. That did the trick. She woke up, cooperated, and then “performed,” wiggling her little fingers on the big screen. I blinked back happy tears. It was incredible to see early signs of her personality taking shape. (No surprise: she now loves dancing and being on stage.)

“The scan is designed to be a thorough check of development, and most pregnancies progress normally,” says Dr. Smith. “When possible, take a deep breath, stay present, and allow yourself to enjoy seeing your baby move, stretch, and take shape. This appointment is not only about reassurance — it’s also a meaningful moment.”

The 20-week scan can be a bonding experience — with your baby, your partner, and even your provider — as you build trust that your pregnancy is progressing well and that you’re truly on your way to motherhood.