Chorionic Villus Sampling | Fetal DNA

In some cases, couples have CVS carried to ensure their baby will be totally healthy and abort the child if they find out it will suffer from a condition. Women who fall pregnant at an older age are considered to be at a higher risk of having a baby with birth defects and might be encouraged to undergo CVS or an amnio to ensure there are no complications.

When it comes to prenatal paternity testing, it is likely that non invasive sampling techniques will take over and that CVS and amniocentesis as means of fetal DNA sampling for paternity testing will no longer be used.

How is Chorionic Villus Sampling carried out?

 

Chorionic villus sampling is done by an OBGYN who will insert a catheter into the womb via the cervix. It is also possible to have CVS done transabdominally rather than through the cervix. The latter method means the womb is entered via the abdomen and this procedure has a slightly lower probability of miscarriage.

An ultrasound will be used to determine the position of the baby. The tube will be inserted so as to reach the placenta and a sample of chorionic villi taken.

What are the risks?

Chorionic villus sampling and amniocentesis are highly invasive tests – both require entering the womb. These procedures can create excessive stress on the womb and the baby.

With CVS, the risk of miscarriage is very small, around 0.5 – 1%. Leakage of amniotic fluid and infection are also possible. It is important to remember that the leakage of amniotic fluid can have very serious consequences, it can affect the baby’s lung and stunt their development, in other words, the baby will have under developed lungs.  If the levels fall too low the baby can be starved of oxygen and die.

Prenatal Paternity Testing and CVS

Chorionic Villus sampling is one way of getting access to the unborn baby’s DNA. It is quite normal to want to know who the father of the child is if you have had multiple partners. The OBGYN in charge of carrying out the CVS will insert a tube into the vagina so as to obtain samples of the finger-like protrusions that line the wall of the uterus which are known as chorionic villi. The chorionic Villi and the fetus are made up of the same genetic material and hence, this is an excellent fetal DNA sample to be used in a prenatal test.

Some mothers will opt for an abortion if the results of the prenatal test do not match the man they hoped was the father. Depending on the time frames in which abortions are legal in the country in question, the expectant mother must choose a DNA fetal sampling technique and work within a time frame. As a prenatal testing method, Chorionic villus sampling has the advantage of being carried out earlier in the pregnancy than amniocentesis.