What does the test involve?
First of all, an ultrasound scan is done to check how far advanced the pregnancy is. A fine needle is passed through the abdomen, and a sample of about 20ml (four teaspoons) of the amniotic fluid surrounding the foetus in the uterus (womb) is taken. This fluid sample contains DNA from the foetus. Amniocentesis can be carried out in a hospital outpatient department, and the woman being tested is awake and aware of what is happening during the test. It usually takes only a few minutes.
Is it painful?
Women who have had the test generally say it is no more painful than having a blood test or an injection.
How accurate is the test?
Amniocentesis results are as accurate as CVS results. The accuracy varies from one condition to another. Your geneticist will discuss this with you before you take the test.
Is the test safe?
There is a slight risk (about half to one percent) of miscarriage. Otherwise it is not thought to harm the baby. Women are advised to avoid strenuous exercise for a few days following the test.