First trimester (11-13 weeks) screening tests includes a blood test combined with an ultrasound. This testing can detect up to 85% of Down’s syndrome and up to 98% of Trisomy13, Trisomy 18 and Turner’s syndrome. This test is performed at another doctor’s office.
For women over 35 or with a personal or family history of chromosomal defects a blood test is available at 10-18 weeks which identifies more than 99% of fetuses with the four most common genetic defects: Down’s, Trisomy 13, 18 and Turner’s syndrome.
Second trimester (15-20 weeks) screening blood test called a MSAFP is done at 15 weeks in our office. This test predicts fetal risk for spinal cord defects (neural tube defects), Down’s syndrome and Trisomy 18.
At 18-20 weeks an ultrasound will confirm your baby’s growth, your due date and can detect 35% of fetal birth defects, but misses 65% of all birth defects.