What does the First Trimester Screening test involve?
The combined First Trimester Screening test has two separate components: • A blood test (ideally taken at 10 weeks gestation) • An ultrasound examination (ideally performed at 12-13 weeks gestation) By combining maternal age, the results of the blood test and the ultrasound each woman can be provided with a risk of the pregnancy being affected by a chromosomal disorder such as Down Syndrome. The test does not tell you that your pregnancy does or does not have this condition, it merely provides information that the pregnancy is at reduced risk (the most likely result) or increased risk (this occurs in 3-5% of pregnancies). For women whose pregnancies screen at increased risk a specific test (chorion villus sampling or amniocentesis is required to actually determine if the fetus is affected.
