At your mid-trimester scan, you’ll see your baby’s position, size and anatomy so you and your care team can prepare for a safe delivery.
The 20-week ultrasound can be one of the longest appointments of your prenatal care. During this scan, also called the second trimester scan, a sonographer will measure your baby’s growth and see how they’re doing in utero.
“The 20-week scan is focused on evaluating the fetal anatomy and checking that your baby is growing appropriately,” said Sybil B. Tremblay, a registered diagnostic medical sonographer at Monroe Carell Jr. Children’s Hospital at Vanderbilt. “This mid-trimester ultrasound helps your care team prepare for a healthy birth.”
At this stage, many moms have already had an ultrasound to confirm the expected due date and check for multiples. “The 20-week scan is more focused on evaluating the fetal anatomy and checking that your baby is growing appropriately,” said Tremblay. “This mid-trimester ultrasound helps your care team prepare for a healthy birth.” The scan is conducted between 19 and 22 weeks.
“The 20-week scan is more focused on evaluating the fetal anatomy and checking that your baby is growing appropriately. This mid-trimester ultrasound helps your care team prepare for a healthy birth.”
What happens at the 20-week ultrasound?
Your 20-week scan will most likely be an abdominal ultrasound. Your health care provider will put warm gel on your abdomen and then glide a transducer over the gel to create the image. On a screen, you will be able to see an image of your baby, which your provider might print for you to take home. Your sonographer will be looking at:
- Key anatomy, including heart structures, the brain and internal organs
- Anatomical measurements such as head circumference, abdominal circumference and length of the long bones
- The position of your placenta and where it connects to the umbilical cord
- The amount of amniotic fluid in your uterus
- Fetal behavior and activity
- Blood flow patterns, which might be color-coded in red or blue to show the direction of the blood flow
- The baby’s sex
If you are waiting until birth to find out the sex of the baby, you can let your provider know at the beginning of the appointment to make sure they don’t mention it to you.
How long will the ultrasound appointment take?
The whole appointment, including check-in time, could take 90 minutes. “A long scan doesn’t mean that anything is wrong,” Tremblay said. “Based on your baby’s position, it might just take a while for us to complete all the necessary measurements.”
What should I wear to an ultrasound scan?
Comfortable clothing is always a plus! Since the sonographer will be scanning your abdomen, many moms wear a shirt and pants instead of a dress to this visit. A small amount of gel might end up on your clothing, so go for something washable.
Can I bring my partner or family to the visit?
At Vanderbilt Health, your partner or family is welcome to join for prenatal visits, including ultrasounds. “I’ve had patients bring spouses, moms, sisters and even close friends,” said Tremblay. If a child is accompanying you to an ultrasound appointment, you will need to have another adult with you to supervise since you’ll be lying down for the scan.
What will happen if my provider sees anything concerning on the scan?
If your provider sees a possible anomaly on the scan, you will be referred to the Reed Family Maternal Fetal Clinic at Vanderbilt to reassess and confirm with another ultrasound. At this appointment, you will speak to a maternal-fetal medicine doctor about the ultrasound findings. Depending on the diagnosis, you may also meet with other specialized providers along with a genetic counselor and a social worker. You will learn more about your baby after the birth. Until then, an ultrasound can give valuable information so your health care providers can give you and your baby the best care possible.
Expert care for you and your baby
Each pregnancy and delivery is unique and yours should be too. Learn more about how Vanderbilt Health’s obstetrics and maternal fetal medicine teams bring together nationally ranked expertise and personalized care from your first prenatal visit to delivery and beyond.
To learn more, call 615-343-5700 or schedule an appointment online.
