Amniocentesis (amnio) and chorionic villus sampling (CVS) are prenatal tests that can diagnose - or, far more often - rule out, certain types of birth defects, such as Down's Syndrome. The two procedures test for most of the same birth defects. One important exception is neural tube defect such as spina bifida, which is only detected by amniocentesis and NOT by chorionic villus sampling.
Do I need prenatal testing?
What is my risk of having a baby with chromosomal defects?
Why is amnio or CVS...