AMNIOCENTESIS

What is amniocentesis?

Amniocentesis is an invasive diagnostic test that analyses cells, DNA and metabolites in the fluid surrounding the baby (amniotic fluid). The cells in the amniotic fluid come mainly from the fetus, so the chromosomes of these cells are the same as those of the fetus.

How is amniocentesis performed?

Under ultrasound guidance, a very fine needle (finer than the one used for chorionic villus sampling) is passed through the skin of the mother's abdomen, and 15-20 ml of amniotic fluid is drawn from the amniotic sac around the fetus and sent to the laboratory.

Amniotic fluid consists of fetal urine, so the amount removed for testing is replaced within just a few hours.

The procedure takes one minute, and we listen to the baby's heartbeat immediately afterwards.

Does amniocentesis hurt?

According to women who have had it, amniocentesis does not hurt. Some mild discomfort, in the sense of pressure, is to be expected. No local anaesthetic is used, as the amniocentesis needle is finer than a local anaesthetic needle and the procedure lasts one minute

When and why is amniocentesis performed?

Amniocentesis can be performed from the 15th week of pregnancy until the end of pregnancy. Ideally, however, it is recommended between the 16th and 20th weeks of pregnancy, while for chromosomal testing the 32nd week is recommended as the upper limit, because after that stage the amniotic fluid becomes more diluted and it is more likely that the laboratory will not obtain a result.

Indications

• The test is performed for specific indications, such as:
• Abnormal nuchal translucency screening.
• Abnormal alpha-fetoprotein / triple test.
• Suspicious ultrasound findings.
• A previous pregnancy with a fetus affected by a chromosomal abnormality.
• Perinatal infection (toxoplasmosis, rubella, etc.).
• Parents who are carriers of genetic disorders, such as thalassaemia, cystic fibrosis, etc.
• Maternal age (over 35).
• At the request of the pregnant woman, because of severe anxiety about possible chromosomal abnormalities.

What should I expect after amniocentesis?

During the first 24 hours you can expect period-like cramps or even pain in the lower abdomen. This is normal, as is occasional light vaginal spotting.

A simple painkiller that is safe in pregnancy, such as paracetamol (Depon), often helps.

It is not normal to have sharp abdominal pain, fever, vaginal bleeding or leakage of amniotic fluid ("waters breaking"). In any of these cases you should seek medical advice immediately.

When will I have the results?

The first results for chromosomal abnormalities such as Down syndrome are usually available in two to three days (PCR). The fetal karyotype (culture) and information on other abnormalities / syndromes / disorders / infections are available within two weeks of the amniotic fluid sample. We will contact you as soon as we have the results.

What are the risks of amniocentesis?

The risk of miscarriage reported in the international literature is around 1 in 1,000. A very small risk of maternal infection (1 in 1,000) has been reported, so it is advisable to record the mother's temperature over the following 48 hours. If there is a fever, a clinical assessment and possibly antibiotic treatment are recommended.