For Down Syndrome and Open Neural Tube Defect Risk Analysis, first and second trimester tests are performed together. Before the result of the test performed in the first trimester is given, the second trimester tests are also run, and the results are given by combining the two. The first stage is most accurately performed at 11 weeks of gestation, but any time between 10 and 13 weeks is acceptable. The second stage is most accurately performed at 15 or 16 weeks and up to a maximum of 22 weeks.
Interpretation:The interpretation of these tests should definitely be done by the doctor. In general: What to do in the first phase: Ultrasound scan to accurately determine gestational age and measure the thickness of the nuchal translucency (NT) (an area at the back of the baby’s neck), Blood sampling to determine the concentration of pregnancy-associated plasma protein-A (PAPP-A), You will be given a blood sample kit and offered a date for a repeat blood sample to be taken for the second stage of the test What to do in the second stage: 1. Taking a second blood sample to determine the concentrations of the following markers: Alpha-fetoprotein (AFP) Free ß human chorionic gonadotropin (free ß-hCG) Free Estriol (uE3) Inhibin-A 2. Integrating the measurements from the first and second stages into a single screening result. The NT measurement and the levels of the five blood markers, together with the patient’s age, are used to determine the risk of a Down’s syndrome pregnancy. In Down’s syndrome pregnancies, PAPP-A, AFP and uE3 levels tend to decrease, while NT measurements, free ß-hCG and inhibin levels tend to increase. The AFP level in the second blood sample is also used to determine an increased risk of open spina bifida or anencephaly.
Sample: Arm venous blood. Nonfasting
Working day: Everyday
Result Time: Two days at 6 PM
