Amniotic fluid test is voluntary and the prospective parents themselves must request that the test be conducted.
What is amniotic fluid test
In the womb, the baby lies and floats in a sack filled with amniotic fluid. The fetal membranes are the walls of the bag. In a amniotic fluid test, a small amount of amniotic fluid is extracted and analyzed. The sample is taken by inserting a thin needle through the abdomen and anterior uterine wall into the amniotic fluid cavity. An ultrasound examination is performed throughout the procedure so that the needle does not reach the fetus.
What information can the amniotic fluid test provide?
In the amniotic fluid are cells from the fetus. These cells contain the same chromosomes (inheritance mass) as the child’s cells and can thus provide information on if any chromosome defect exists (including Down syndrome). Some rare hereditary diseases can also be detected by such a study.
It is important to be aware that an examination response that shows normal chromosomes does not provide any guarantees that the child is healthy. The most important answer an amniotic fluid test can provide is whether the child has chromosome abnormalities or some hereditary diseases. Amniotic fluid test does not provide information on spinal hernia.
When is the amniotic fluid performed?
In Sweden, most regions offer amniotic fluid samples from the year the woman turns 35. When deciding that an amniotic fluid test is to be performed, a comprehensive assessment of the parents and the risk factors is made. In the following cases, a test can often be helpful:
- In parents of children with chromosome disease.
- If one or both parents are carriers of a chromosome aberration.
- In parents of children with serious illness as a result of damage to a sex chromosome (the X chromosome). In these cases, the mother is often perfectly healthy but carries the diseased gene. The woman has two X chromosomes and only one of these is passed on to the child. Boys have only one X chromosome (the other is a Y chromosome from the father) and if they get their mother’s diseased gene they develop disease.
- In women / couples who have previously had a child with a congenital metabolic disease, where it is possible to investigate if the disease exists.
- If an ultrasound examination has shown signs of a possible chromosome abnormality in the fetus.
- If the woman / couple is in a very difficult life situation, amniotic fluid tests may be granted in special cases.
In most cases, the test itself is performed after 15 full weeks of pregnancy. In most cases, a quick analysis is made of the three most common chromosomes. Answers to this analysis will come within a week. In a complete analysis, it takes about two weeks to get a response to the test and if the examination shows that the fetus has a severe injury, the parents are immediately called for genetic guidance.
Are there any risks with an amniotic fluid test?
The test can hurt a little and takes almost 20 minutes. You do not need any stunning to do the test. When sampling, an ultrasonic device is used to ensure that the needle ends up correctly and does not come into contact with the child. There is a small risk of miscarriage as a result of the procedure, about 1 in 100–200 who undergo the test gets miscarriage.