The anatomy scan is a detailed ultrasound performed between 18 and 22 weeks of pregnancy, and preparing for it is straightforward. You don’t need to fast, take any special medications, or do anything dramatically different from your normal routine. A few simple steps can help the appointment go smoothly and give the sonographer the clearest possible images of your baby.
When to Schedule It
Most providers schedule the anatomy scan between 18 and 22 weeks of gestation. This window exists because the baby is large enough for the sonographer to see detailed structures clearly, but small enough that there’s still room to move and get good angles. If your provider gives you a choice, scheduling closer to 20 weeks tends to hit the sweet spot. Scheduling too early can mean some structures aren’t fully developed enough to evaluate, which increases the chance you’ll need a follow-up.
What to Eat and Drink Before the Scan
You can eat and drink normally before your anatomy scan. There’s no fasting required. Some providers recommend having a snack or a small meal about 30 minutes before the appointment. Research has shown that fetal activity increases significantly in the 30 minutes after a mother consumes sugar, so having a juice, a piece of fruit, or a light snack may encourage your baby to shift positions during the scan. This isn’t a guarantee, but it can help.
Whether you need a full bladder depends on your provider and how far along you are. Some clinics ask you to drink 32 ounces of water (about four glasses) starting one hour before your appointment. A full bladder pushes the uterus into a better position for imaging early in the scan, particularly for checking the placenta and cervix. You can use the bathroom as needed while you keep drinking. Other clinics skip this step entirely for 20-week scans since the uterus is already high enough. Call ahead or check your appointment instructions so you know what your specific office expects.
What to Wear
Wear a two-piece outfit. The sonographer needs access to your bare abdomen, so a separate top and bottom is the easiest option. You’ll pull your shirt up and tuck a sheet or towel into the waistband of your pants. Most patients don’t need to change into a gown. A dress works too, though it’s slightly less convenient. Jewelry and watches are fine to keep on.
What Happens During the Appointment
The scan typically takes about 30 minutes, though it can run longer if your baby is in a tricky position or moving around a lot. The sonographer applies warm gel to your abdomen and uses a handheld probe to capture images. They’ll work methodically through a long checklist of structures: the brain, spine, heart (including its four chambers), kidneys, stomach, bladder, limbs, fingers, toes, and facial features. They also measure the baby’s head, abdomen, and thigh bone to confirm growth is on track, and they check the placenta’s position and your amniotic fluid levels.
The sonographer may be quiet for stretches while they concentrate on getting specific images. This is normal and doesn’t mean something is wrong. Some will narrate what they’re looking at, while others prefer to focus and let the doctor review everything afterward. If your baby is curled up or facing your spine, you might be asked to walk around, drink water, or lie on your side to encourage repositioning.
This is also the appointment where you can typically learn the baby’s sex, if you want to. Let the sonographer know at the start whether you’d like to find out or prefer to keep it a surprise.
Bringing a Partner or Guest
Most clinics allow one or two guests (18 years or older) in the room during the scan. Policies vary, so confirm with your provider beforehand, especially if you want to bring more than one person. Many facilities do not allow young children in the ultrasound room and do not provide childcare for siblings during your visit. If you’re planning to bring a support person, make sure they know the appointment could take 30 to 45 minutes or longer.
Ask ahead of time about recording policies. Some clinics allow you to take photos or video on your phone, while others restrict recording during the diagnostic portion and only allow it at the end when the sonographer shows you the baby.
Why You Might Need a Follow-Up Scan
About 12% of anatomy scans are incomplete on the first visit, meaning the sonographer couldn’t capture every required image. The most common reason is simply that the baby wasn’t cooperating. If the baby’s hands are covering the face, the spine is turned away from the probe, or the legs are crossed, certain measurements become impossible to get. Higher body mass index and earlier gestational age also make it harder to get complete images.
A callback for a repeat scan doesn’t necessarily mean something is wrong. A study of nearly 19,000 anatomy scans found that the biggest factor in whether a repeat was recommended was which sonographer and physician performed the initial scan, not clinical red flags. Some sonographers recommended repeats less than 5% of the time while others recommended them over 45% of the time, even with similar patient populations. So if you’re asked to come back, it often reflects imaging standards rather than a concern about your baby.
That said, sometimes a follow-up is scheduled because the provider wants a closer look at a specific structure, like the heart or kidneys. Your provider should explain why a repeat is needed and what they’re looking for.
Tips for the Day Of
- Arrive early. You’ll likely need to check in, fill out paperwork, and possibly use the restroom one last time before the scan starts.
- Have a snack 20 to 30 minutes before. Something with natural sugar, like juice or fruit, can encourage fetal movement and make it easier to get clear images.
- Skip lotion on your belly. Some lotions or oils can interfere with the ultrasound gel’s ability to transmit sound waves clearly.
- Bring a list of questions. If there’s anything specific you want to know, like placenta position or cervical length, write it down so you don’t forget in the moment.
- Be patient. If the baby isn’t in the right position, the appointment may take longer than expected. Some clinics will have you take a break and walk around before trying again.