Amniocentesis is used to examine the fetus for chromosomal abnormalities. This pamphlet explains who the test is offered to, how it is carried out and what it looks for. You can also read about the procedure reflected risks of amniocentesis, and how you will receive the results.

Who will be offered amniocentesis?

• Pregnant women where the likelihood of the fetus having Down’s syndrome (trisomy 21) is greater than 1:300 or if the risk of trisomy 18 or trisomy 13 is greater than 1:150
• Pregnant women who have an increased risk of chromosomal abnormalities in the fetus
• Pregnant women where an abnormality has been detected in the fetus by an ultrasound scan which may be due to chromosome abnormalities.

How is an amniocentesis performed?

An amniocentesis is performed after 16 weeks of pregnancy (16 weeks + 0 days). First an ultrasound will be carried out to check the amount of amniotic fluid and the placement of the placenta and the fetus in the uterus. The skin will then be washed with a disinfectant liquid. A thin needle is then inserted through the abdominal wall. By the needle approximately 30 ml of amniotic fluid is drawn. A local anaesthetic is not used.

The procedure will take 10-15 minutes. We recommend that you rest afterwards for about 20 minutes before going home. Take it easy the rest of the day.

What should I be aware of?

You can go to work the next day unless you have a physically demanding job. If this is the case, you should take the next day off. You may feel some discomfort after the procedure such as muscle soreness, period-like cramping and a downward pull in your abdomen.

The discomfort often disappears within 24 hours and does not require treatment. If needed, you can take a 1g paracetamol tablet, available over-the-counter (always read the patient information leaflet).

NOTE: Contact a doctor if you begin bleeding heavily, if amniotic fluid begins to leak, or if you experience strong pains. You may contact the Ultrasound Clinic during our telephone hours. Outside these hours, dial 1813.

Risks in connection with amniocentesis

The risk of miscarrying after amniocentesis is approximately 0.5%. If you are expecting twins, the risk is approximately 2%. Most miscarriages that happen after amniocentesis will occur within 1-2 weeks.

What can an amniocentesis detect?

Amniocentesis can be used to diagnose chromosomal abnormalities in the fetus. The most well-known is Down’s syndrome.

Amniocentesis does not guarantee a healthy and normal child since it cannot diagnose all chromosomal abnormalities or genetic diseases.

Getting the results

The sample will be sent to the Chromosome Laboratory at Rigshospitalet. The sample will be thoroughly analysed using micro-array.

The analysis will take about 10 working days. If the results are normal, you will receive the results in your E-boks as soon as they are available. If the results are not normal, you will be contacted by telephone.

Further information about the amniocentesis

If you would like to know more about amniocentesis, you can call the Ultrasound Clinic to book an appointment.

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