A: What is an amniocentesis?

Amniocentesis is a test typically offered between 15 and 20 weeks of pregnancy to women when there are fears of birth defects.

The test is used to try to detect Down's syndrome or a range of other chromosomal or genetic disorders – and is offered to women with a family history of such conditions or whose blood tests or ultrasound scans have shown a higher possibility of problems.

Women may also be offered this test if they are over 35 and missed screening tests earlier in pregnancy - as the risk of Down's syndrome increases with age.

During the procedure a fine needle is passed through the mother's abdomen into the amniotic fluid around the baby in the womb. A small sample of this fluid is taken out with a syringe and sent for testing.

Depending on what is being tested for, results may take between three days and three weeks.

The test shouldn't hurt but there might be some discomfort. There are risks involved, including a chance of miscarriage in 0.5 to 1% of tests.

Counselling is always offered before the test so that parents can think about the risks and what they would do if the results showed an abnormality.

Parents may feel that it would be best for their family to end the pregnancy, or they may choose to use the knowledge to get ready for the birth.

For most women, the test will give a definite positive or negative result. If a disorder is diagnosed, the hospital should discuss this fully, provide parents with information, and give the option to talk to a specialist.


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