Chorionic villus sampling

Overview
Chorionic villus sampling (CVS) is a form of prenatal diagnosis to determine genetic abnormalities in the fetus. It entails getting a sample of the chorionic villus (placental tissue) and testing it. It is generally carried out only on pregnant women over the age of 35 and those whose offspring have a higher risk of Down syndrome and other chromosomal conditions.

The advantage of CVS is that it can be carried out 10-12 weeks after the last period, earlier than amniocentesis (which is carried out at 15-18 weeks).

Risks
CVS is similar to amniocentesis in terms of fetal mortality (0.2 to 0.3%). 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 known as oligohydramnios which is low amniotic fluid Level. If the resulting olighydramnios is not treated and the amniotic fluid continues to leak it can result in the baby developing what is called hypoplastic lungs (underdeveloped lungs). If the baby develops hypoplastic lungs the lungs do not have a chance to mature, and the baby can die shortly after birth.

It is extremely important after having a CVS that the OB/GYN follow the patient closely to ensure the patient does not develop infection. The OB/GYN should also measure the patient's fundal height with a tape measure (this should be done on every prenatal visit) and routinely ultrasound the patient to ensure the baby has sufficient amniotic fluid.