Published by Bupa's health information team, December 2008.
This section contains answers to common questions about this topic. Questions have been suggested by health professionals, website feedback and requests via email.
Your doctor will explain to you the risks and benefits of having amniocentesis. Only you can decide whether the test is right for you.
Making a decision about having a diagnostic test during pregnancy can be difficult. You may be making this decision alone or with your partner.
To help make the decision that is best for you, your doctor should discuss the following information with you:
You may want to know more about the disorder or disorders which can be detected by amniocentesis. You may also want to know more about what is involved in ending a pregnancy and how you may feel afterwards.
If you are fairly certain that you will end this pregnancy if the results are abnormal, you might want to find out as soon as possible about a disorder. In this case, you may decide that amniocentesis isn't the best option. You may choose to have an alternative diagnostic test such as chorionic villus sampling, which is performed earlier in pregnancy.
There is a small risk that you may miscarry as a result of having amniocentesis.
Amniocentesis is a test done during pregnancy. A sample of the amniotic fluid that surrounds the baby in the womb is taken usually by passing a fine needle through your abdomen (tummy). This test is only done if your baby is at risk of having a serious genetic disorder, such as Down's syndrome. It is usually done after 15 weeks of pregnancy.
Amniocentesis may cause a miscarriage if the needle punctures the placenta or introduces infection into the womb. About one in 100 women who have amniocentesis will miscarry as a result of this procedure. The risk is dependent on the skill of the doctor as well as technique. A more experienced doctor performing amniocentesis may have a higher success rate and a lower rate of procedure-related miscarriage.
Don't shy away from asking your doctor about his or her level of experience in this technique. You can also ask the hospital or clinic the test is being performed at to see their outcome data for amniocentesis. This will give you an opportunity to see how the hospital or clinic is performing in relation to other hospitals, and their complication rate for amniocentesis.
If you have any concerns about this test, speak to your doctor or midwife.
For the majority of genetic disorders, there isn't a treatment or cure. You will need to consider what is best for you and the baby.
Amniocentesis usually gives a clear result - the chromosomes are either normal or not. Your doctor will explain what the results mean. For the majority of genetic disorders, there isn't a treatment or cure.
How you choose to proceed with the pregnancy will depend on what the results mean to you, your family and your unborn child. There are several options to consider.
These decisions may be difficult and it's a good idea for you to discuss the issues with your partner, your family, your doctor and other health professionals before deciding to have amniocentesis.
Yes, you can have the amniocentesis test if you are Rh-negative and your baby is Rh-positive. You will be given an injection which helps to stop your immune system from reacting with your baby's blood.
Your red blood cells carry many antigens on their surface. The most important of these antigens belong to the ABO system and the Rh system. The D antigen is the most important antigen of the Rh system. People with the rhesus D (RhD) antigen are referred to as RhD-positive, and those without it as RhD-negative. A baby inherits its blood type from both parents. Therefore a mother who is RhD-negative can carry a baby who is RhD-positive.
There is a risk that during an invasive procedure such as amniocentesis, some of your baby's blood may enter your bloodstream. If this happens your immune system will recognise the RhD antigen on your baby's blood cells and make antibodies against it (anti-D antibodies). This process is called sensitisation or alloimmunisation.
As your pregnancy develops (or in a future pregnancy), your immune system may produce more anti-D antibodies. These may cross the placenta and bind to RhD antigen on the surface of your baby's red blood cells. The antibody-coated fetal red blood cells are removed from your baby's circulation. Your baby can develop anaemia if the red blood cells are removed faster than they are produced. Severe anaemia can cause fetal heart failure, fluid retention and swelling (hydrops), and intrauterine death.
The risk of sensitisation can be reduced if you are given an anti-D immunoglobulin before or after amniocentesis. If and when your baby's blood enters your bloodstream, the anti-D immunoglobulin neutralises the fetal antigen so that your immune system won't produce antibodies against it.
This information was published by Bupa's health information team and is based on reputable sources of medical evidence. It has been peer reviewed by Bupa doctors. The content is intended for general information only and does not replace the need for personal advice from a qualified health professional.
Publication date: December 2008
Visit the amniocentesis health factsheet for more information.