What scans can you expect in your second trimester?
The second trimester is an exciting and often easier stage of pregnancy. Here's some insight into the what, when and why of ultrasounds during this time.
Obstetric ultrasounds or ‘scans’ as they are commonly known, are highly anticipated events during a pregnancy where parents-to-be are able to gain a unique view of their developing baby while it’s still tucked away in the womb. During the first half of the pregnancy, up until 20 weeks gestation, a woman is generally unable to feel her baby moving. So, these precious moments when you are having a scan, albeit being very surreal, can be enough to reassure you that your baby is safe and well and growing and thriving within you.
WHAT IS ULTRASOUND?
Ultrasound is a non-invasive diagnostic imaging procedure that produces pictures of the inside of the body using high frequency sound waves. The sound waves travel from a small probe called a transducer, through the skin and into the body. The sound waves bounce off different tissues within the body in a different way, depending on the tissue, and the sound waves that return back to the transducer are converted into electricity. The transducer sends the electrical signals to a computer which converts them into an image. These images are captured in real time and can show the structure and movement of the body’s internal organs. They can also show blood flowing through blood vessels; this is known as a Doppler ultrasound.
ULTRASOUND IN PREGNANCY
During pregnancy, ultrasounds are performed to evaluate a baby’s development. The sonographer will put a clear odourless gel on your skin which is needed to allow the sound waves to be sent and received by the transducer. The sonographer passes the transducer over your skin overlying your uterus and baby. The transducer sends out ultrasound waves and picks them up again when they bounce back. The transducer converts the sound waves to electrical signals which are sent to the computer to create an image of your baby which is displayed on the screen. Most women will have a 12 week scan, a 20 week scan and one or more growth scans during their uncomplicated ‘singleton’ pregnancy. However, mothers carrying twins or triplets should be prepared to have more scans.
In Part One, The First Trimester we ran through the early dating scan and the 12 week scan, so let’s jump onto the next ones you need to know about…
THE 20 WEEK ANATOMY SCAN
The 20 week scan is the most detailed scan of your baby as your baby’s organs are just the right size to be more easily seen on ultrasound; big enough but not too big. If you decided not to have NIPT earlier on, then the sonographer may also be able to see the sex of your baby on the anatomy scan if baby’s legs are separated enough to allow easy visibility of this area.
THE SONOGRAPHER WILL:
+ Take measurements to check the growth of your baby. These measurements are less reliable at checking your dates compared to the dating and 12 week scans, but if you haven’t had either of these, then the anatomy scan is the next best scan to check your due date.
+ Check baby’s anatomy: brain, face, heart, diaphragm, stomach bubble, kidneys, bladder, spine, arm bones, hands, leg bones, toes.
+ Check the position of your placenta.
CAN'T WAIT TO SEE BABY'S FACE?
4D scanning offers enthusiastic (slash impatient!) parents a sneak peek of their baby’s face while still in the womb. It’s still not quite the same as the real thing, but the detail is definitely up a level on the traditional 2D scans, and you get a lovely memento for the baby album. Between 26 to 32 weeks is the ideal time for scanning as there is more amniotic fluid and your baby has developed some soft tissue about the face. Be aware that it’s not always possible to get a good image though – baby’s position, the maternal size and the amount of amniotic fluid play a big role in the quality of the 4D scan, and are all out of the sonographer’s control!
WHAT IS 4D ULTRASOUND?
Ultrasound units now all have advanced ultrasound machines with 3D and 4D capabilities. These machines produce amazing images with the computer creating the face of your baby to look like they’ve actually taken a photo. There are certain medical reasons for having a 3D image such as looking for a cleft lip. If you are wanting a 3D image, then you may need to pay an extra cost, and they are usually only possible if time allows after the medical ultrasound examination of your baby has been completed. You always need a referral from your LMC to book any scan.
