CVS – How Does the Procedure Work?

A CVS procedure can be done in the doctor’s office by a high-risk pregnancy doctor called a perinatologist. CVS is an outpatient procedure, meaning you can usually go home soon afterward. Most women find that it can be uncomfortable and many compare it to having intense menstrual cramps, but generally do not experience considerable pain beyond that.

The point of the procedure is usually to obtain tissue from the placenta to send to the lab for testing. The lab can look at the cells from that tissue, and inside those cells at the chromosomes. Most of the time, the baby and the placenta have the same chromosomes. To learn more about chromosomes, visit our Genetics 101 page.

Less than 1% of the time, the placenta’s chromosomes may be different from the baby’s chromosomes; this is called confined placental mosaicism. If there is an abnormal test result and the lab is able to confirm that there is confined placental mosaicism in the sample, then the most likely thing is that the abnormal result is only in the placenta and not in the baby. The only way to tell for sure before the baby is born would be to do another test called an amniocentesis.

The tissue for CVS can be obtained in one of two ways:

  • A catheter can be used to reach the placenta vaginally
  • A small needle can be inserted into the abdomen to reach the placenta

Whether a CVS is done via the abdomen or vaginally is dependent on many factors, including where the placenta is located and who the doctor is performing the procedure. The procedure generally takes less than a couple minutes from start to finish.

Because CVS is an invasive procedure, there is an approximated less than 1 in 200 (0.5%) chance that it may cause complications that could lead to a miscarriage. This also means that over 99.5% of women who undergo CVS testing do not have a procedure-related miscarriage. To help limit the risk for complications, your doctor may give you special instructions to limit strenuous physical activity for the few days following your procedure.

Depending on the type of testing that is performed, CVS can look for chromosome conditions, such as Down syndrome, or other genetic conditions, but cannot rule out all birth defects or genetic conditions.

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  • The type of results may vary depending on the type of testing that is done on the CVS sample. The four main types of testing that can be done on CVS samples are: traditional chromosome analysis (also called a karyotype), chromosomal microarray, familial mutation testing, and fluorescent in-situ hybridization (FISH).…
  • This can be difficult news to hear, and everyone handles situations like this in different ways. It is often helpful to talk with your doctor or genetic counselor to make sure any questions that you have are answered, particularly if the results are complex or confusing. Even if you are…
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  • Because the placenta and the baby come from the same cells, they have exactly the same amount of chromosomes most (98-99%) of the time. In approximately 1-2% of all pregnancies, the placenta can actually have a different chromosome makeup from the baby. This is called confined placental mosaicism (CPM). When…

Last updated on Apr 7th, 2018