Obstetric dating ultrasound
It involves a blood test and measuring the fluid at the back of the baby's neck (nuchal translucency) with an ultrasound scan.This is sometimes called a nuchal translucency scan.
A trained counsellor in the area of diagnosis and screening should be available, as should a quiet room for breaking bad news about the baby.
You can ask your midwife or doctor before the scan if this is the case. Find out more about what happens during a pregnancy ultrasound scan.