The 20 weeks ultrasound examination can be done from 19 to 22 weeks. The scan is usually performed transabdominally. Sometimes, it may be necessary to do the scan transvaginally. The aims of 20 weeks ultrasound examination are to:
- 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 preterm labour (especially in the first pregnancy, or in case of a previous preterm delivery) and
- Measure the blood flow in the uterine arteries to assess the risk of growth restriction and pre-eclampsia.
- The specific condition: some conditions, such as spina bifida, anencephaly (deficient development of the skull) and gastroschisis (a defect in the abdominal wall), are detected in more than 90% of cases. Some conditions (such as cerebral palsy or autism) are usually NOT seen on ultrasound. Some conditions (such as certain forms of dwarf growth or hydrocephalus) only develop later on in pregnancy.
- 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.
GeneralYour husband or partner is very welcome to join you during the ultrasound scan. It is preferable to limit the number of visitors. To bring small children along is usually boring for the child and distracting for yourself. An empty bladder is preferable during the ultrasound scan. Please do not drink tea or coffee or eat chocolate beforehand to make the baby move during the ultrasound examination – this can result in the baby moving so much that the examination is actually more difficult.