What is the principle of this test?
Since the placenta and the foetus have the same embryonic basis, chromosome count determination in the placenta provides the chromosome count in the foetus.
How is this test performed?
This test is done on an outpatient basis. Under sonographic control, a thin needle is introduced through the abdominal wall into the placenta, from which a small tissue sample is taken.
What are the advantages of this test?
The greatest advantage of this test is that it may be done following the completed from 11th week of pregnancy, so that the result is available as early as in the 12th-13th week.
What are the disadvantages of this test?
The greatest disadvantage is the risk of having to repeat the sampling. For a variety of technical reasons (mozaic, small tissue amount, absence of mitoses), approximately 6% of samples have an inconclusive diagnosis and the test has to be complemented by amniotic fluid sampling.
What are the CVS risks?
The greatest risk is a 0,5% possibility of inducing an abortion. This risk has to be added to the risk of natural pregnancy interruptions, which in this period amounts to about 3%.
Potential additional risks are bleeding and/or pain. These problems usually disappear in a few days. Extremely rare complications include infections.
When is this test inappropriate?
We do not recommend this test to women with past medical history of bleeding, pain in the lower abdomen, or vaginal discharge.