Technical Summary of Work:
Chromosomal abnormalities are a leading cause of developmental delay in children. Trisomies 21, 18 and 13 and sex chromosome aberrations are the most frequently occurring chromosomal abnormalities. Definitive prenatal diagnosis currently requires invasive sampling followed by chromosome analysis. However, invasive tests are costly and pose an inherent risk of procedure-related complications including miscarriage. Therefore, following appropriate screening, invasive tests should be performed only in high-risk pregnancies.
Screening based on maternal age in combination with second-trimester serum analyses has been established with detection rates of 60–84% for a false-positive rate of 5%. However, late diagnosis of chromosomal abnormalities and pregnancy termination at an advanced gestational age could incur unnecessary anxiety for families. In addition, women prefer to undergo first-trimester screening if the choice is available3.
First-trimester risk assessment of common chromosomal aneuploidies is based on a combination of maternal age, maternal serum-free β-human chorionic gonadotropin (fβ-hCG), pregnancy-associated plasma protein-A (PAPP-A) and fetal nuchal translucency thickness (NT) at 11 to 13 + 6 weeks. In various prospective studies the detection rate ranges from 74% to 93% for a fixed false-positive rate of 5%. Additional first-trimester ultrasound markers, namely absent nasal bone (NB), reversed ductus venosus (DV) flow and tricuspid regurgitation (TR), have separately been found to increase the effectiveness of trisomy 21 screening.
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