In Australia, women are offered two ultrasounds throughout their pregnancy. One is offered between 11 and 13 weeks and is known as the 12 week scan. The second is known as the 20 week scan. The 12 week scan is offered to confirm the dates of your pregnancy, forms part of the screening for downs syndrome, will check on general growth and development of the foetus, and will show if you are having more than one baby. It’s a good idea to have your partner or someone else with you at this appointment, to support you through it and share your excitement.
The 12 week scan is used to screen for the risk associated with the most common congenital chromosomal abnormalities, such as Down Syndrome. This screening is done in conjunction with a blood test, which is done at around 10 weeks pregnant. The combination of the blood test results, the mother’s age and the ultrasound imaging help care-providers analyse their patient’s risk of Down Syndrome.
Looking for a Heart Beat
For most parents, the 12 week scan will be the first time they see their baby, and they are able to enjoy the thrill of seeing their baby’s heart beating. So, while it is mostly a wonderful and exciting appointment, its primary purpose is to look for problems with the pregnancy. The first thing the sonographer will look for is the baby’s heart beat.
How It’s Done
In most cases the ultrasound will be performed by scanning the abdomen, but in some cases a vaginal scan will need to be done, as this provides clearer images. Through these images, measurements of your baby can be taken to ensure their development is on track and they are roughly where they should be. The scan usually takes around half an hour to perform.
Other things that the sonographer will check for during the scan include:
- the size of the foetus and developing placenta
- measure the amount of fluid at the base of the foetus’ neck; through this measurement an individualised risk assessment for Down Syndrome can be made
- check for other physical abnormalities
- check the mother’s reproductive anatomy such as the uterus, fallopian tubes and pelvic region for other possible complications
- measurements for the Crown Rump length, which is the length from its head to its bottom.
Generally, your sonographer will talk you through the scan and will tell you if everything looks to be going well. If required, the sonographer may seek clarification or a second opinion from another doctor while performing the scan. This can cause some parents to worry, but in most cases they will tell you what they are looking for and why. You will usually be given your scan results immediately and your Down Syndrome risk within a few hours of the scan.
How To Interpret Your Results
If you are found to be ‘high risk’ you will be offered further diagnostic testing. It is important to understand that a ‘low risk’ score does not guarantee that there are no chromosomal abnormalities. If you are aware of any genetic disorders in your family or your partner’s family, it is best seek counselling from your care giver around this issue, as the 12 week scan alone may not be able to provide you with answers.