Chorionic villus sampling (CVS) is a form of prenatal diagnosis to determine chromosomal or genetic disorders in the fetus. It entails getting a sample of the chorionic villus (placental tissue) and testing it. CVS can be carried out 10-13 weeks after the last period, earlier than amniocentesis (which is carried out as early as 14-16 weeks).It is the preferred technique before 15 weeks
Use as early as 8 weeks in special circumstances has been described.
It can be performed in a transcervical or transabdominal manner.
Possible reasons for having a CVS can include:
• Mother's age of 35 years or greater
• Abnormal first trimester screen results
• Increased nuchal translucency or other abnormal ultrasound findings
• Family history of a chromosomal abnormality or other genetic disorder
• Parents are known carriers for a genetic disorder
CVS carries a higher risk of harming the fetus than amniocentesis (miscarriages occur in around 1 in 100 to 1 in 200 cases with CVS, versus around 1 in 1,600 with amniocentesis. Apart from a risk of miscarriage, there is a risk of infection and amniotic fluid leakage. The resulting amniotic fluid leak can develop into a condition of low amniotic fluid level. If not treated and the amniotic fluid continues to leak it can result in the baby developing hypoplastic lungs (underdeveloped lungs). Additionally, there is a risk of CVS causing digit-reduction defects in the fetus if performed before 11 weeks (0.07%-0.10%).
It is important after having a CVS that the OB/GYN follow the patient closely to ensure the patient does not develop infection.
A small percentage (1-2%) of pregnancies will have confined placental mosaicism, where some but not all of the placental cells tested in the CVS will be abnormal, even though the pregnancy is unaffected. Cells from the mother can be mixed with the placental cells obtained from the CVS procedure. Occasionally if these maternal cells are not completely separated from the placental sample, this can lead to discrepancies with the results. This phenomenon is called Maternal Cell Contamination (MCC). CVS cannot detect all birth defects. It's used for testing chromosomal abnormalities or other specific genetic disorders only if there is family history or other reason to test.
My personal experience:
As I explained in my case the sampling was performed trascervically. The hole thing took no more than 15 minutes. It is almost painless, just like a normal Pap test. Its, uncomfortable and you have to add the fact that you´ll find yourself very stressed thinking about your baby´s wellbeing. Choose carefully your doctor and you´ll be much more relieved.You must stay in bed and make no effort for at least the following three days. The results are ready in 48 hours. Seems quick but when you are in bed waiting it feels eternal.