Genmark

Earliest Week: 14
Latest Week: 22

Price: £195

A second trimester ultrasound scan measuring the nuchal fold and four biochemical blood markers are used to calculate the risk of Down’s syndrome and other chromosomal abnormalities. A risk for neural tube defects and abdominal wall defects is screened for if the blood test is taken after 15 weeks. The overall Down’s syndrome detection rate is 77% and the false positive rate is 2.8%.

Screen negative is a risk less than 1 in 250.