Amniocentesis involves the examination of cells in the fluid from around the fetus (amniotic fluid).
The cells in the amniotic fluid originate from the baby and so the chromosomes present in these cells are the same as those of the baby.
How is amniocentesis done?
Amniocentesis involves passing a thin needle into the uterus in order to remove a small volume of amniotic fluid. The needle is carefully observed using ultrasound scan.
The fluid is fetal urine and the amount removed by amniocentesis reaccumulates within a few hours.
The procedure lasts 1 minute and afterwards we check that the fetal heart beat is normal.
What should I expect after amniocentesis?
For the first couple of days you may experience some abdominal discomfort or period-like pain. You may find it helpful to take simple painkillers like paracetamol.
If there is a lot of pain, bleeding, loss of fluid from your vagina or if you develop a temperature please seek medical advice.
When can I expect to get the results?
The rapid results for Down's syndrome and other major chromosomal defects are usually available within 3 days (FISH or PCR). The results for rare defects and the full culture can take 2 weeks. As soon as we get the results, we will call you to let you know.
What are the risks associated with amniocentesis?
The risk of miscarriage due to amniocentesis is about 0.6% and this is the same as the risk from chorion villus sampling. If you were to miscarry due to the test, this would usually happen within the next five days.
Some studies have shown that when amniocentesis is performed before 16 weeks there is a small risk of the baby developing club feet. To avoid this risk we never perform amniocentesis before 16 weeks.