Amniocentesis Test in Pregnancy

What is amniocentesis? When being given pregnancy advice by their GP or midwife, some women will be recommended amniocentesis. This is a diagnostic test which can detect a serious, or potentially serious, condition in an unborn baby. Amniotic fluid surrounds the fetus in the womb. It contains waste products from the baby as well as cells which have been shed from her skin, therefore it contains the baby’s DNA. Samples of this fluid taken during amniocentesis gives a clear of developing conditions. These could be: Chromosomal conditions such as: • Down's syndrome – affecting physical appearance, mental development and learning abilityrn• Edward's syndrome – causing severe physical and mental abnormalitiesrn• Patau’s syndrome – a rare, serious condition. Babies with this condition usually die within a few days. Inherited blood disorders such as: • sickle cell anaemia – where red blood cells are an unusual shape and texturern• thalassaemia – affecting the body’s ability to create red blood cellsrn• haemophilia – affecting the blood's ability to clot Neural tube defects As the embryo develops its neural tube forms the baby’s spine and nervous system. A defect in the neural tube can lead to conditions such as spina bifida, which can cause learning difficulties and partial paralysis of the legs. Musculoskeletal disorders Certain conditions can affect the baby’s bones and muscles (the musculoskeletal system). For example muscular dystrophy is an inherited condition that causes muscles to gradually weaken. Other genetic conditions Amniocentesis can help diagnose a number of genetic conditions, such as Marfan syndrome which affects the tissues providing support and structure in the body. When is amniocentesis carried out? It’s usually performed in the second trimester between weeks 15 to 20. Performing it earlier may increase the risk of miscarriage or causing club foot in the foetus. When is it offered? If you’ve already had a pregnancy with fetal problemsrnIf you’ve a family history of a conditionrnIf you’re over 35rnIf any earlier tests suggest there may be a problem How is it performed? An ultrasound scan is carried out before and during amniocentesis, to allow the specialist to continually check the position of the fetus and decide on the best place to insert the needle which will withdraw some amniotic fluid. The abdomen is cleaned with an antiseptic solution and a long, thin needle is inserted through the abdominal wall. It may cause a sharp, stinging sensation. The area is sometimes, but not always, numbed with anaesthetic. The needle passes into the amniotic sac that surrounds the foetus and the syringe removes a small sample of fluid. It takes about ten minutes. What happens next? If the amniocentesis test finds a problem with the fetus, it may be possible to treat the baby while she is still in the womb. If a serious abnormality is detected, parents will be given all the pregnancy advice thy need to decide whether to continue or terminate the pregnancy.