Amniocentesis is a special kind of diagnostic test that looks at genetic material from the fluid surrounding your baby, so that any chromosomal abnormalities can be identified. Amniocentesis is most often done during the second trimester, after 15 weeks. It is usually carried out on women who have been identified as being at risk of having a baby with a genetic condition like Down’s Syndrome. This may be because of a family history of disease, because they are thirty-five or older or due to the combined test showing a significantly increased risk.
Occasionally an amniocentesis may be performed later in pregnancy, if certain problems are suspected. These conditions include potential chorioamnionitis, or an infection in the sac around the baby. It can also help if there is a risk of premature delivery, since amniocentesis fluid can be used to estimate maturity of the foetal lungs.
Using ultrasound to guide the procedure, an expert will insert a long, thin needle through the skin of your abdomen. It will go through the wall of the womb and into the sac around your baby. A small amount of the amniotic fluid will be withdrawn for analysis.
The experience can be a little uncomfortable and you may notice some mild cramping or blood spotting. It’s a good idea to take it easy and rest for 48 hours following the procedure. Sadly, between one and two in two hundred women will have a miscarriage, following the procedure, often because of the introduction of infection at the time of the test. To minimize risk, it should be performed by a physician experienced in the procedure, however unfortunately there is still a danger of pregnancy loss.
The amniocentesis results can take 3 days to give an accurate and reliable diagnosis of Down’s, Edwards’ and Patau’s Syndromes. A full karyotype of your baby’s genetic make-up, that will be able to definitively tell you if your baby is affected by a chromosomal abnormality, as well as letting you know their sex, can take up to three weeks.
It can be devastating to be told that your baby is affected by Down’s Syndrome or another serious condition. Please understand that you are not alone. Speak to your doctor or midwife and ask about counselling and support available to you.
Further investigations may be available to look in greater detail at your baby, and look for linked problems, such as heart defects, so that you have all the information you need to help make the difficult decisions about continuing with or ending a pregnancy.
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