| Chorionic villus sampling | |
|---|---|
 Micrograph showing chorionic villi—the tissue that is collected in CVS.H&E stain. | |
| Other names | CVS |
| ICD-10-PCS | 16603-00 |
| ICD-9-CM | 75.33 |
| MeSH | D015193 |
| MedlinePlus | 003406 |
Chorionic villus sampling (CVS), sometimes called "chorionicvillous sampling" (as "villous" is the adjectival form of the word "villus"),[1] is a form ofprenatal diagnosis done to determinechromosomal orgenetic disorders in thefetus. It entailssampling of thechorionic villus (placental tissue) and testing it for chromosomal abnormalities, usually withFISH orPCR. CVS usually takes place at 10–12 weeks' gestation, earlier thanamniocentesis orpercutaneous umbilical cord blood sampling. It is the preferred technique before 15 weeks.[2]
CVS was performed for the first time inMilan by Italian biologistGiuseppe Simoni, scientific director ofBiocell Center, in 1983.[3]Use as early as eight weeks in special circumstances has been described.[4] It can be performed in a transcervical or transabdominal manner.[2] Although this procedure is mostly associated with testing forDown syndrome, overall, CVS can detect more than 200 disorders.[5]
Possible reasons for having a CVS can include:[citation needed]
The risk of miscarriage in CVS is estimated to be potentially as high as 1–2%. However some recent research has suggested that only a very small number of miscarriages that occur after CVS are a direct result of the procedure.[6] Apart from a risk of miscarriage, there is a risk of infection andamniotic fluid leakage. The resulting amniotic fluid leak can develop into a condition known asoligohydramnios, 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).[7][8]
Additionally, there is also mild risk of limb reduction defects associated with CVS, with the risk being higher the earlier the procedure is carried.[9]
It is important after having CVS that theobstetrician follows the patient closely to ensure the patient does not develop infection.[citation needed]
Recent studies have discovered that chorionic villi can be a rich source of fetal stem cells, multipotentmesenchymal stem cells.[10][11][12]
A potential benefit of using fetal stem cells over those obtained from embryos is that they side-stepethical concerns among anti-abortion activists by obtaining pluripotent lines of undifferentiated cells without harm to a fetus or destruction of an embryo. These stem cells would also, if used to treat the same individual they came from, sidestep the donor/recipient issue which has so far stymied all attempts to use donor-derived stem cells in therapies.[citation needed]
Artificial heart valves, working tracheas, as well as muscle, fat, bone, heart, neural and liver cells have all been engineered through use of fetal stem cells.[13]
The first fetal stem cells bank in US is active in Boston, Massachusetts.[14][15][16][17]
A small percentage (1-2%) of pregnancies haveconfined placental mosaicism, where some but not all of theplacental cells tested in the CVS are abnormal, even though the pregnancy is unaffected.[18] Cells from the mother can be mixed with theplacental cells obtained from the CVS procedure. Occasionally if these maternal cells are not completely separated from theplacental sample, this can lead to discrepancies with the results. This phenomenon is called Maternal Cell Contamination (MCC).[18] CVS cannot detect all birth defects. It is used for testingchromosomal abnormalities or other specificgenetic disorders only if there is family history or other reason to test.[citation needed]
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