Indications of performing Chorionic villus sampling, or Amniocentesis

• have had a high risk screening test for Down syndrome
• have had a previous pregnancy affected with a genetic disorder
• or your partner have one or more relatives affected with a genetic disorder, which means you are at greater risk of having a child with a genetic disorder, such as cystic fibrosis, thalassaemia or sickle cell disease
• have received a result from a scan which shows certain abnormal ultrasound features, such as fluid collection at the back of the baby's neck (nuchal translucency), or a congenital heart defect which indicates the baby may have a disorder such as Down syndrome. This may be suspected on a scan at 18-22 weeks
• want to know for certain whether your baby has a genetic disorder or not.