Second Trimester Morphology Ultrasound

WHAT IS A SECOND TRIMESTER MORPHOLOGY ULTRASOUND?

A second trimester morphology ultrasound is performed in the middle part of the pregnancy, usually between 20 to 22-week gestations. All pregnant women have this ultrasound as a routine part of their antenatal (pregnancy) care. This ultrasound will check the baby's normal growth and development.

WHAT WILL BE CHECKED ON A SECOND TRIMESTER MORPHOLOGY ULTRASOUND?

1. BABY'S STRUCTURE

We routinely look at the baby's head and brain; face including lips and profile; heart; chest including diaphragm; abdomen including kidneys, bladder and stomach; spine; and limbs including hands and feet. Assessing all these parts of the baby requires a certain level of "cooperation" from the baby, as well as good scanning conditions.
If your baby is not cooperative (mostly related to its position) or other factors make your ultrasound technically difficult (such as the size of the mother's abdomen), we may require more images to be confident that all is well with baby. These images may be obtained later on the same day, or sometimes you may be asked to come back in a few weeks for another review.

2. MEASUREMENTS OF THE BABY

Each measurement is compared to a normal reference range, which varies with gestation. Every individual baby has its own characteristics. For instance, some babies have bigger head measurements or shorter femur measurements than the others.

3. BABY'S HEART RATE AND RHYTHM

varies 120 -180 beat per minute

4. THE POSITION OF THE PLACENTA.

About 2-3% of pregnancies have a low-lying placenta on the second trimester morphology ultrasound. As the uterus grows during the pregnancy into the third trimester, it usually pulls the placenta up and away from the cervix.
Transvaginal ultrasound is often used to get a better look at the placenta, if there are concerns it may be low-lying.We may choose to review the position of the placenta again in the third trimester (around 30-34 weeks) if there are concerns that the placenta remains low-lying.

5. THE AMOUNT OF AMNIOTIC FLUID AROUND THE BABY

6. THE LENGTH OF THE CERVIX

This is especially important if you have a history of premature labour, vaginal bleeding or pain. The length of the cervix is not as important as you get closer to your due date (full term). Transvaginal ultrasound may be required to get a better view of the cervix.

7. THE UTERUS

The uterus is checked for conditions such as uterine fibroids.

8. 3D/4D IMAGES OF THE BABY

Many parents enjoy the bonding experienced when they see their baby on 3D/4D imaging. We aim to obtain good 3D/4D pictures of the baby's face on this scan, but we also think it is important to make sure that the baby is otherwise healthy and growing well. For this reason, the3D/4D images of the baby are often done after the baby has been fully examined when all routine measurements and other images are completed.
The best time to obtain 3D/4D images of baby is between 24 and 32 weeks.

CAN THIS ULTRASOUND DETECT ALL PROBLEMS OR ABNORMALITIES IN MY BABY?

  • Ultrasound can assess the baby's development with great detail, but it cannot detect all problems or abnormalities.
    • Having your ultrasound in a practice with high standards of expertise and experience will improve the chance of detecting abnormalities.
  • Routine ultrasound is one of the best methods we have of checking the baby and helping detect if the mother is at increased risk of certain pregnancy complications.