What is a Fetal Growth Scan ?
Your obstetrician has referred you for an ultrasound scan to assess the baby’s size and the amniotic fluid volume. This type of ultrasound scan is referred to as a fetal growth scan.
Why is growth scan needed?
1. To assess the baby’s growth at any point of time in pregnancy.
2. Your abdomen measures smaller or larger than expected.
3. Previous pregnancy complications.
4. Maternal diabetes or high blood pressure.
Ultrasound imaging uses soundwaves to take pictures. It is radiation free and is not harmful to you or your unborn baby.
What is to be done prior to exam?
Kindly take appointment at least one day prior to exam.
Please come with a comfortably full bladder.
It is helpful to hold off on using any creams or lotions on your belly on the morning of your test. If you have had any previous tests, such as a past ultrasound, bring any medical records that you have.
Kindly turn off your phone/keep it in silent mode before entering the ultrasound room and throughout the examination.
What will happen during the examination?
The scan will be performed in dimly lit room and you would be asked to lie on a flat couch.
Clear(perhaps cold) ultrasound gel will then be applied and the ultrasound specialist will commence the exam. To get optimum views of your baby, slight pressure may have to be applied.
The ultrasound specialist will perform a series of measurements to check the growth of the baby.
These are:
1. BPD and HC: Biparietal diameter and Head circumference (around the baby’s head).
2. AC: Abdominal circumference (around the baby’s waist line).
3. FL: Femur length (the length of the thigh bone).
4. AFI/MVP: Amniotic fluid index/Maximum vertical pocket(measure of fluid around the baby).
The measurements are plotted on a growth chart, according to the number of weeks pregnant that you are at the time of the scan (gestational age). An estimate of fetal weight (EFW) can be calculated by combining the above measurements. The EFW can be plotted on a graph to help determine whether the fetus is average, larger or smaller in size for its gestational age.
If the fetal weight estimate is below the bottom 10 per cent line on the graph, it is considered to be small for gestational age (SGA). If the fetal weight is above the top 10 per cent line on the graph, it is considered to be large for gestational age (LGA).
It is important to note that repeated ultrasound measurements of the same fetus can vary and the estimated fetal weight may be incorrect by as much as 20 per cent.
A fetal growth scan does not routinely check the baby for abnormities.
An ultrasound scan to look for major fetal abnormalities is routinely performed in pregnancy between 18 and 22 weeks gestation which is known as anomaly scan.
What happens after the examination?
You would usually receive the printed report on the same day.
If your baby is growing normally it is reassuring.
If the doctor has any concerns regarding the growth of your baby, you may be advised further testing like assessement of blood flow to your baby(Fetal colour doppler). This will allow you and your baby’s care needs to be assessed and planned.