What it detects
Amniocentesis is a specific test that is able to tell you if your baby has a normal number of chromosomes (46). It can find Down syndrome and other major chromosome abnormalities. A second test is done to measure the amount of alpha-fetoprotein (AFP) in the amniotic fluid. A higher than normal amount may suggest the possibility of a neural tube defect, such as spina bifida. Normal results can take up to 3 weeks. Concerns are usually identified and given to your doctor or midwife within 10-14 days.
If there is a family history of a known problem, other special tests may be done on the amniocentesis sample. You need to discuss this with your doctor or midwife who will refer you to Medical Genetics for additional tests in advance of your procedure.
Five in 100 women have a chance of having a baby with a major birth defect that can be found during the first year of life. The most common defects are cleft lip and palate, clubfeet, heart defects and mental retardation. The results from amniocentesis, CVS or fetal blood sampling will indicate whether or not there are chromosome abnormalities or neural tube defects, but will not be able to rule out other abnormalities.