What does the Quadruple test involve?
A sample of your blood is taken at around 15 or 16 weeks of pregnancy (between 14 and 22 weeks is acceptable). The stage of pregnancy is best estimated by an ultrasound dating scan. The concentration of four substances in your blood will be measured. The four markers are: • alpha-fetoprotein (AFP) • free -human chorionic gonadotrophin (free -hCG) • unconjugated oestriol (uE3 ) • inhibin-A (inhibin) In pregnancies with Down’s syndrome, AFP and uE3 levels tend to be low and free -hCG and inhibin levels tend to be raised. The level of AFP is also used to determine if there is an increased risk of spina bifida or anencephaly. Can any other abnormalities be identified? Yes, the Quadruple test also indentifies pregnancies at a high risk of Edward’s syndrome (trisomy 18). . The risk of Edward’s syndrome can be identified using AFP, uE3 and free -hCG. What is defined as a screen-positive result? Down’s syndrome: If the risk of having a term pregnancy affected with Down’s syndrome is 1 in 200 o
