The 20-week ultrasound, also known as the anomaly scan, is a form of prenatal screening. The main objective of the ultrasound is to establish whether the child has spina bi da or anencephaly. The ultrasound also examines the development of the child’s internal organs. This may reveal other physical defects (see examples). Finally, the ultrasound will establish whether the child is growing normally and whether there is sufficient amniotic fluid.
Some examples of the defects that can be revealed by a 20-week ultrasound include: spina bifida, anencephaly, hydrocephalus, heart defects, a hole or rift in the diaphragm, a hole or rift in the abdominal wall, missing or malformed kidneys, missing or malformed bones, malformed arms and legs.
The result of the 20-week ultrasound cannot guarantee that the child will be healthy. Some defects will not show up on the ultrasound. The procedure does not pose any risk to the mother or child. This ultrasound scan is not ‘just for fun’. The 20-week ultrasound scan is a medical examination.
The aim of this ultrasound scan is not to check the foetus’s gender. If the ultrasound expert happens to notice the gender, he/she will only provide the details at your request. If the 20-week ultrasound reveals any abnormalities, the consequences for your child may not yet be clear. In most cases, you will be offered the option of follow-up testing. You will then be provided with extensive information on the follow-up test in a consultation with the obstetrician, who can also provide support and answer any questions you may have.
You are free to determine whether or not you want testing and what steps to take on the basis of the results.