Accuracy of pregnancy dating scans
Please ask you hospital about this before your appointment.Remember, an ultrasound scan is an important medical examination and it is treated in the same way as any other hospital investigation.You may like someone to come with you to the scan appointment.Most hospitals do not allow children to attend scans as childcare is not usually available.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.
The procedure is carried out in a dimly lit room so the sonographer is able to get good images of your baby. You will then be asked to lower your skirt or trousers to your hips and raise your top to your chest.
The sonographer estimates when your baby is due (the estimated date of delivery, or EDD) based on the baby's measurements.
The dating scan can include a nuchal translucency (NT) scan, which is part of the combined screening test for Down's syndrome.
Ultrasound scans use sound waves to build a picture of the baby in the womb.
The scans are completely painless, have no known side effects on mothers or babies, and can be carried out at any stage of pregnancy.