Open neural tube defects cannot be ruled out by doing noninvasive and can be ruled out by doing ultrasound available amniocentesis. Noninvasive DNA screening is a common pregnancy test that can detect chromosomal abnormalities in the fetus, including trisomy 21, trisomy 18, and trisomy 13. Noninvasive DNA screening does not check for or rule out the presence of open neural tube defects. Ultrasound and amniocentesis can be performed if you want to check for the presence of open neural tube defects in the fetus. Pregnant women who are at high risk of finding open neural tube defects in their fetus during a pregnancy test can seek medical attention for another ultrasound and amniocentesis to confirm the diagnosis.