The Triple Screen test is used for Prenatal Screening of Down Syndrome (Trisomy 21), Edwards Syndrome (Trisomy 18) and Open Neural Tube Defects. The approximate detection rate with this test is 55-65% with a false positive rate of 5%. The double and triple screening tests measures the amounts of two to three substances in a pregnant womans blood: a)free beta hcG b)alpha-fetoprotein (AFP),and estriol (uE3).