Download brochure - 18-20 week obstetric scan
What is the 18-20 Week Obstetric Scan
This scan is usually performed between 18 to 20 weeks gestation to assess the development of your baby and to exclude any obvious problems with the pregnancy. At this stage, most of the organs and structures in the baby have formed and are able to be seen with ultrasound.
During the examination the sonographer (a technologist specially trained in ultrasound) will assess the baby, measuring the circumference and diameter of the head, the circumference of the abdomen and the length of the femur (the bone in the thigh). The sonographer will then look at the major structures in the baby, particularly the brain, heart, spine, kidneys and bladder.
Unfortunately the baby will not always be lying in the best possible position or may still be a little too young (less than 18 weeks), to complete the examination. In these cases it may be necessary for you to come back another day.
Is Ultrasound Safe?
Ultrasound has not been shown to have any harmful effects on you or the baby. In the last 30 years, more than 50 million pregnant women have had diagnostic ultrasound. In these pregnancies, epidemiological studies have shown no increase in fetal abnormalities or childhood malignancy. Similarly no behavioural or neurological consequences have been attributable to ultrasound.
Can my partner or family member be present?
Yes, we would be happy to show the baby to your partner or family member. This person can be with you during the entire scan.
The examination will take approximately 45 minutes. During this time the doctor may also wish to check some aspects of the scan.
Can I find out the sex of the baby?
The sonographer’s ability to determine the sex of the baby will depend upon the age of the baby and whether the baby is positioned in a way that allows for a good image of the organs. If there is good visualisation and it is requested by both parents, the sonographer or doctor will notify you of the likely sex of the baby.
Can we have a video of our baby?
It is not Queensland X-Ray’s policy to provide videos of the examination. If available, we will be happy to provide you with a black and white photo of the baby and give you all the images to take with you.
If I have to come back for a further scan, is there something wrong?
No, not necessarily. Frequently the baby is lying in an awkward position and some aspects of the anatomy cannot be seen. Other times we just need to assess the progress of certain structures with further growth.
If the scan is reported as normal, does that totally exclude any problems with the baby?
With advances in ultrasound we can now see most structures very clearly. There are however some things we cannot see. No matter how detailed the scan we cannot see everything.
Most significant abnormalities ARE detected. If fetal abnormalities are of particular concern to you, there are blood tests and more invasive procedures such as amniocentesis available, which your obstetrician can discuss with you.
Overall, most parents feel the 18 to 20 week detailed ultrasound scan is an exciting and rewarding experience, and have great delight in seeing their baby on the screen. Dads particularly enjoy this experience, and sometimes we even see the baby wave hello on the screen!