Amniocentesis

Alternative Names: Amniotic fluid test, Amniotic cell culture

Amniocentesis tests the amniotic fluid in the uterus around the foetus in order to detect chromosomal abnormalities (e.g. Down’s syndrome), defects in the spine (e.g. Spina Bifida), some rare inherited disorders, and blood-group problems (e.g. Rhesus incompatibility). Ultrasound, an imaging technique that uses sound waves, shows where the foetus is in the uterus. A local anaesthetic is then injected into the skin and a long, thin needle is guided into the uterus. A small sample of fluid is then taken and sent for tests, which take about 3 weeks. There are small risks of miscarriage and infection. It is worth considering, before the amniocentesis, what you would do if any of the tests are positive.

What is it?
Amniocentesis is a test where amniotic fluid (the fluid within the uterus, around the foetus) is withdrawn for testing.

It is usually performed in a clinic or hospital and takes less than an hour.

Why is it done?
Amniocentesis reveals important information about the foetus. It is used to detect:

• Down’s syndrome (a chromosomal abnormality)
• Spina Bifida (defect in the structure of the spine)
• Several rare inherited disorders
• Rhesus (Rh) incompatibility (a blood-group problem)

What happens?

Before – how to prepare
You will need to sign a consent form. You will need to have a full bladder.

During – how the test is done
Ultrasound (imaging technique that uses sound waves) is used to visualise the foetus and its position within the uterus (so the doctor does not injure the foetus with the needle). The skin over your abdomen will be scrubbed clean. Local anaesthetic is usually injected into the skin. A long, thin, needle is guided into the uterus and a small sample of fluid is withdrawn. There may be some stinging and slight pain when the needle is inserted and some women complain of lower abdominal cramps.

After the test
You will be told to rest for at least 24 hours after the procedure, to reduce the risk of miscarriage. It usually takes 3 weeks before the results are known (cells need to be cultured/grown).

Risks and Compilations
There is a small risk of miscarriage associated with this procedure as well as a small risk of infection. Any severe cramps or vaginal bleeding should be reported to your doctor immediately.

Special Issues
In the case of Down’s syndrome and Spina Bifida, it is important to consider what you would do in the event of a positive result. Termination of pregnancy may be an option and it is worth considering this carefully, before the test.

Short Description
Amniocentesis tests the amniotic fluid in the uterus around the foetus in order to detect chromosomal abnormalities (e.g. Down’s syndrome), defects in the spine (e.g. Spina Bifida), some rare inherited disorders, and blood-group problems (e.g. Rhesus incompatibility).

Keywords
amnio, pregnancy, amniotic fluid test, amniotic cell culture, birth defects, downs syndrome, amniocentesis