The triple test assesses the risk of having a Down's baby based on:

• maternal age
• maternal serum markers - alpha feta protein, unconjugated oestriol and total human chorionic gonadotrophin.

Serum is taken from 15-20 weeks gestation, ideally 16 weeks. A high hCG, low AFP and low oestriol suggest a Down's child. Results are expressed in terms of the risk of having a Down's child eg. 1 / 145. Detection rates range from 45-65% with a 5% false positive rate. Those with a risk greater than 1 in 200 are offered amniocentesis.

Other risks may also be detected eg. a high AFP suggests a neural tube defect.

Patients need to be counselled:

• the value of the test needs explanation

Note that the triple test was known as the Barts test in some areas.

Improved combined methods of screening are now available (see link below).