Down Syndrome or Trisomy 21 is one of the most common autosomal chromosomal disorders of the new-born. The severity of the syndrome includes intellectual disability, congenital heart malformation, immune system disorders, impaired gastrointestinal development, and severe physical development. This test uses only the first trimester markers NT, free bHCG and PAPP-A. The best time for the test is approximately 11th week of gestation. However, 10th to 13th weeks is also acceptable. When the blood sample is taken, an ultrasound should be performed on the same day.
Interpretation:Low PAPP-A, high NT, free bHCG may be indicative of a pregnancy with DOWN syndrome. This test does not give information about neural tube defects. If the risk is 1/150 or higher, amniocentesis or CVS (chorionic vilus sampling) may be recommended. If the risk of Edward’s syndrome is 1/100, an ultrasonography scan will be recommended. DR (sensitivity) is 85% and FPR (false positive rate) is 0.2%. The detection rate for Down’s syndrome is 84.80% and 84.8% of women will have a positive result. The remaining 15.8% may have a Down syndrome pregnancy even if they get a negative result. The FPR is 2.2 per cent. This means that even if the pregnancy is not a Down syndrome pregnancy, 2.2% of pregnant women will still have a positive screening result. The OAPR is 1:9, meaning that in women in the positive screening group, for every 9 unaffected pregnancies, 1 will be an affected pregnancy.
Sample: Venous blood from the arm. Fasting status is not required.
Working day: Every day
Result Time: 2 days at 6 PM
