Anomaly Scan

When can this Scan be done

• The 20 weeks ultrasound examination can be done from 19 to 22 weeks.

The aim of the Anomaly Scan

• Evaluate the structural development of the baby, with special attention to the brain, spine, face, heart, stomach, bowel, kidneys and limbs. If you wish, the fetal gender can be determined.
• Determine the growth of the baby
• Determine the position of the placenta and the amount of amniotic fluid
• Measure the length of the cervix if needed to assess the risk of pre-term labour (especially in the first pregnancy, or in case of a previous pre-term delivery)
• Measure the blood flow in the uterine arteries to assess the risk of growth restriction and pre-eclampsia.

More about Anomaly Scans

At 20 weeks pregnant, baby is the size of a banana. He or she weighs about 280g and measures about 165 millimeters crown to rump. Your baby is swallowing more these days, which is good practice for his digestive system. He’s also producing meconium, a black, sticky by-product of digestion. This gooey substance will accumulate in his bowels, and you’ll see it in his first soiled diaper (some babies pass meconium in the womb or during delivery).

Can All Abnormalities Be Seen?

• An amazing amount of detail can often be seen. However, it is important to realize that not all parts of the baby show up well with ultrasound. No ultrasound examination can ever guarantee a normal fetus. The best centres in the world consistently report on the limitations of ultrasound and its inability to detect all fetal abnormalities.
• Up to half the fetal heart defects will not be seen. Some of these are only minor, but some may not be apparent until the fetus is bigger, later in the pregnancy. Many bone growth problems, forms of dwarfism, will only be possible to be suspected late in pregnancy and the diagnosis is made on x-rays taken after the baby is born.
• How well the baby is seen on ultrasound. This in turn depends on the quality of the ultrasound equipment and the skill of the person doing the ultrasound, but also on factors like the pregnancy duration, the position of the baby and placenta, the amount of amniotic fluid and the amount of fluid or fat or possible scar tissue in your abdominal wall. Especially if your BMI is above 30, it can be tricky to visualize every detail well.