If you are in your first trimester, you might have heard of the term Chorionic Villus Sampling (CVS) from your gynaecologist. Experts from KK Women's and Children's Hospital (KKH) give a breakdown of what CVS is, why it is important, and what to look out for. 

Chorionic villus sampling (CVS) is a procedure in which an obstetrician withdraws a small amount of the placenta tissue. This is done by inserting a biopsy needle through the mother's abdomen into the placenta. The obstetrician will use ultrasound to guide the needle during the procedure so as not to harm the unborn child. For this procedure, local anaesthesia will be given.

The procedure is performed on an outpatient basis and takes only a few minutes.

The needle will cause some pain when it penetrates the uterus, but the pain should not last long and should not hurt more than an injection into any other part of the body.

After the tissue has been withdrawn, the removal of the needle should cause no further discomfort. The tissue is then sent to the laboratory for special tests.

Why is chorionic villus sampling necessary?

Chorionic villus sampling is done for the detection of chromosomal disorders and genetic diseases such as thalassaemia.

Chromosomes carry genes that pass certain characteristics from parents to their children. When there are too many or too few chromosomes, or there is a defect in a chromosome, birth defects usually occur.

Down Syndrome is the most common chromosomal disorder. It causes mental retardation and other health problems such as heart defects. Other less common chromosomal disorders may lead to serious handicaps and death.

Thalassemia is an inherited blood disease, which is transmitted by a gene. If both parents have the thalassamia trait, the chance of having a child with thalassaemia major is 25%.

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