| Chorionic villus sampling | |
|---|---|
| Intervention | |
Model of human embryo 1.3 mm. long. (Villi of chorion labeled at lower right.) |
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| ICD-10-PCS | 16603-00 |
| ICD-9-CM | 75.33 |
| MeSH | D015193 |
Chorionic villus sampling (CVS), sometimes misspelled "chorionic villous sampling",[1] is a form of prenatal diagnosis to determine chromosomal or genetic disorders in the fetus. It entails sampling of the chorionic villus (placental tissue) and testing it. CVS usually takes place 10–12 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.[2]
CVS was tested for the first time by Italian biologist Giuseppe Simoni, scientific director of Biocell Center, in 1983.[3]
Use as early as 8 weeks in special circumstances has been described.[4]
It can be performed in a transcervical or transabdominal manner.[5]
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Possible reasons for having a CVS can include:
Risk of miscarriage in CVS in about 0.5 - 1%. 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 oligohydramnios is not treated and the amniotic fluid continues to leak it can result in the baby developing hypoplastic lungs (underdeveloped lungs).
Additionally, there is also mild risk of Limb Reduction Defects associated with CVS, especially if the procedure is carried out in earlier terms (before 12th week of pregnancy).[7]
It is important after having CVS that the OB/GYN follow the patient closely to ensure the patient does not develop infection.
A small percentage (1-2%) of pregnancies have confined placental mosaicism, where some but not all of the placental cells tested in the CVS are abnormal, even though the pregnancy is unaffected.[8] 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).[8] CVS cannot detect all birth defects. It is used for testing chromosomal abnormalities or other specific genetic disorders only if there is family history or other reason to test.
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