Fetal Anomaly Scan (FAS) also called a mid-pregnancy ultrasound scan, when you are between 18 weeks and 20 weeks plus six days pregnant.
Seeing your baby on a screen can be a really exciting event. You can also take your partner, friend or family member along to share the experience with you.
The vast majority of babies are normal. However all women, whatever their age, have a small chance of delivering a baby with a physical or a mental problem. Many such abnormalities can be diagnosed and ruled out with the Fetal Anomaly Scan.
This ultrasound scan is very accurate but unfortunately it cannot diagnose 100% of congenital abnormalities. If the scan is complete, we would expect to pick up at least 95% of cases of spina bifida, 80% of cases of cleft lip or palate, and 60% to 70% of cases of congenital heart disease. This scan can also identify 50% to 70% of cases of Down syndrome, but the First Trimester Screening (FTS) test is better for this. Because 30% to 50% of cases of Down syndrome appear normal on ultrasound, only an amniocentesis can give you this information for certain. It is also important to realise that ultrasound scans in pregnancy do not detect problems like cerebral palsy or autism.