Growth Pregnancy Scan

This Growth pregnancy scan is performed to determine the fetal position, growth, and size by measuring the size of the fetal head, abdomen and thigh bone. We will also examine fetal movements, placental position, amount of amniotic fluid and assess the blood flow from the placenta by colour flow Doppler when indicated. We check to see if the baby may be feet-first or buttocks first (breech), side-on (transverse) or at an angle (oblique) presentation. The placental site will also be assessed to rule out placenta praevia. We would include standard measurements, estimated fetal weight and heart rate.

Procedure Includes:

• Ultrasound exam
• Medical obstetric growth ultrasound report
• Glossy picture print

Why Would I Need a Growth Baby Scan?

• Assessment of the baby’s size and growth: You may be concerned that your baby is too small, not growing, or too large. Perhaps you have a condition that may affect the growth of the baby, such as high blood pressure or diabetes.
• Review of the placenta: You may wish to review the position of the placenta if there were concerns of a low-lying placenta on an earlier scan or if you have unexplained vaginal bleeding. Most women with a low-lying placenta seen at 18-20 weeks will not have a problem by the time they reach their third trimester. As the uterus expands, it tends to pull the placenta up and away from the cervix.
• You may have symptoms such as pain, contractions, vaginal bleeding or reduced fetal movements. A growth ultrasound can help provide reassurance that your baby is okay.
• Review of the baby’s anatomy: You may wish to review a change in regards to a concern or which was noted on an earlier ultrasound examination.
• Assess the position of the baby: You may be curious about the position of the baby (for example, if baby is lying in a cephalic (head down position). This becomes more important towards the end of the pregnancy when the delivery of your baby is near.
• You have a twin/multiple pregnancy: Twins are at a higher risk of growth issues during the pregnancy. Depending on the type of twin pregnancy, your babies may also be at an increased risk of other complications and you may just want to be reassured.

What Will Be Assessed On a Growth Baby Scan:

Measurements of the baby:

A Growth ultrasound scan will commonly measure:

• baby’s head - biparietal diameter (BPD) and head circumference (HC).
• baby’s abdomen - abdominal circumference (AC).
• baby’s leg - femur length (FL).

Each measurement is compared to a normal reference range, which varies with gestation. Every individual baby has its own characteristics (for example, some babies have bigger head measurements or shorter femur measurements). These characteristics are often similar to the baby’s parents (for example, one parent may have a big head or short legs).

Measurements outside the normal range are not always significant, especially if the difference is minimal. Your baby will be carefully assessed and additional measurements taken if there are concerns about significant deviations from normal.

Head, abdominal and femur measurements are combined in a special formula to estimate the weight of your baby.

The size of the baby (the estimated fetal weight).

The estimated fetal weight (EFW) is compared to the size of other babies at the same gestation.

This is often expressed as a percentile:

• An EFW on the 50th percentile is an average sized baby.
• An EFW less than the 10th percentile is a small baby.
• An EFW more than the 90th percentile is a big baby.

This ultrasound weight is an estimation of your baby’s size only – there is a recognized 15% error in this estimation, with your baby being either 15% smaller or 15% larger than the estimated weight. While we recognize there is this error present in our estimation of your baby’s size, ultrasound remains the best way your doctor has of checking the size of your baby.

Every baby has its own individual growth pattern, and this can be monitored if there are concerns.

The amount of amniotic fluid around your baby:

The amount of amniotic fluid or liquor is usually expressed as an “amniotic fluid index” (AFI). This index is calculated by measuring the maximal vertical distance of fluid in each quadrant (or corner) of the pregnancy sac. There is a wide range for the normal volume of amniotic fluid in a pregnancy, and this range will vary with gestation.

Sometimes, the volume of fluid around your baby may be increased (polyhydramnios), or perhaps the volume of fluid around your baby is below the normal range (oligohydramnios). Changes in the fluid volume are not always significant, especially if the difference is minimal. If the fluid level is low you may be required to rest.

The blood flow in the umbilical cord (the umbilical artery):

The blood flow in the umbilical artery (which is in the baby's umbilical cord) will be measured when indicated and is known as an umbilical artery Doppler.

This may help assess the function of the placenta and the growth of your baby. This measurement is usually expressed as a resistance index (RI). Babies that are not growing normally (known as growth restricted) may show progressive changes in the resistance of this artery. Changes in this measurement is not always significant, especially if the difference is minimal.

The baby’s heart rate and rhythm:

Your baby’s heart rate will vary, just as it does in adults. Most babies have a heart rate between 120-180 beats per minute.

The position of the baby:

This ultrasound will tell us what position the baby is lying in:

• Head down (cephalic).
• Bottom down, with the head at the top of the uterus (breech).
• Sideways, across the uterus (transverse).

The position of the baby is more important towards the end of the pregnancy, when the baby is due for delivery.

The position of the placenta:

Your health care provider will want to know that the lowest edge (inferior margin) of the placenta is not lying too close to the cervix. This is known as placenta praevia or a low-lying placenta.

Transvaginal or translabial ultrasound may be required during your third trimester ultrasound if there are concerns about the position of the placenta, to get a better look at the cervix area and lower edge of the placenta. (the tranasvaginal or translabial ultrasound is not performed at our centre after the first trimester) If there is a concern we will advise you to contact your health care provider.

The anatomy of the baby:

As your baby grows during the pregnancy, it fills up the space inside the uterus, pressing its body against the wall of the uterus. This means some parts of the baby may be more difficult to see later in the pregnancy, especially hands and feet. The baby’s position will also affect how well some structures are seen, including the heart, face, and spine.

Some of the structures which we try to routinely review in a growth pregnancy ultrasound includes the baby’s kidneys, bladder and face.

The length of the cervix:

This is especially important if you have premature labour, vaginal bleeding or pain. The length of the cervix is not as important for us to know as you get closer to your due date (full term). Often the cervix is obscured from view by the baby’s head.

Sometimes a transvaginal ultrasound may be required to get a better view of the cervix. (not perfromed transvaginally at our centre but we will advise you to contact your health care provider)

What Will My Baby Look Like On An Ultrasound:

Beautiful and clear images of your baby, especially baby’s face, are often seen on a growth scan later in pregnancy.

It is natural for many parents to think that as their baby grows bigger, it is always easier to see the baby on ultrasound. This is unfortunately not always true. Many parents find it more difficult to understand what they are looking at. Ultrasounds performed later in the pregnancy usually focuses on one part of the baby at a time for example, baby’s head. The baby’s size pervents us from viewing the whole body at once like we would on a 12 weeks scan. 

 

Many factors influence what parts of the baby can be seen to include the position of the baby, the volume of amniotic fluid (low fluid makes it harder to see) and the size of the mother’s abdomen (increasing skin thickness makes it harder to see). The sonographer will attempt to obtain the best possible images of your baby, and to explain these images as much as possible.

 

It is good for parents to anticipate seeing their growing baby, but not to be too disappointed if this ultrasound proves difficult to understand or the images of baby’s face are impossible to obtain.

Please Note: For Twins please add €70

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