How accurate are dating scans
The sonographer will put ultrasound gel on your tummy and tuck tissue paper around your clothing to protect it from the gel.
The gel makes sure there is good contact between the machine and your skin. It is this probe that sends out ultrasound waves and picks them up when they bounce back.
Ultrasound scans use sound waves to build a picture of the baby in the womb.
The scans are painless, have no known side effects on mothers or babies, and can be carried out at any stage of pregnancy.
for more information on what may happen if a scan or other screening test suggests an abnormality.If you are overweight or your body tissue is dense, sometimes this can reduce the quality of the image because there is more tissue for the ultrasound waves to get through before they reach the baby.If it's difficult to get a good image, the scan may take longer or have to be repeated at another time.For example, you may be offered further tests, such as amniocentesis, that have a risk of miscarriage.The first scan is sometimes called the dating scan.
If you're offered further tests, you will be given more information about them so you can decide whether or not you want to have them.