Integrated Test for Down Syndrome Screening

Maternal serum screening is a noninvasive method. Its principle is to assay mother’s blood for multiple biochemical markers and calculating the risk upon parameters measured and some other risk factors like age, previous abortions, gender, number of fetuses, previous Down Syndrome pregnancies and some other behavioural and cultural paremeters. There are some different tests for predicting Down’s syndrome with noninvasive maternal blood and fluid samples dependent or independent of gestational week. .One of these are: Integrated Test: Uses first and second trimester markers which are NT (Nuchal Translucency (thickness,a space at the baby’s neck), PAPP-A (Pregnancy Associated Plasma Protein), AFP(Alpha fetoprotein), hCG(Total human chorionic gonadothropin), uE3(Unconjugates estriol) and Inhibin-A. This is a two stage test. First stage involves NT and PAPP-A, the second stage involves AFP, uE3, bHCG and Inhibin A
Interpretation: Using mother’s age and these 5 markers, the results are interpreted as Low PAPP-A, AFP, uE3 with high NT (Nuchal Translucency measured by ultrasound on the same day with the sample), hCG, Inhibin A reflect Down’s syndrome The level of low AFP in the second trimester is also used as a marker of increased risk of spina bifida or anencephaly. If it is 2.5 times higher than the average level the result will be screen-positive neural tube defect. An ultrasound scan will be offered. Integrated test also gives risk information for Edward’s Syndrome (Trisomy 18) with the results of NT, PAPP-A, AFP, uE3 and free bHCG If the risk is 1/150 or higher, the patient will be offered amniocentesis. Integrated tet has a detection rate of %90, meaning %90 of a screen positive pregnancies, will be effected with Down Syndrome while %10 with Down syndrome babies will receive negative test result. The FPR (False positive rate), will be %1.3, meaning that %1.3 of the healthy pregnancies will have a screen positive result, %98.7 of the women with negative result, will have healthy babies. Odds of being affected given a positive result (OAPR) will be 1:5, meaning that, among with a screen positive result, only 1 woman will have Down Syndrome baby, the other 5 will have healthy babies.
Sample: Arm vein blood. Nonfasting
Working day: Everyday
Result Time: First trimester sample result is calculated together with the second trimester blood sample results. This complete result is 3 days after the second sample, at 6:00 PM