Chorionic villus sampling

Template:Short description Template:Infobox medical intervention

Chorionic villus sampling (CVS), sometimes called "chorionic villous sampling" (as "villous" is the adjectival form of the word "villus"),<ref>A PubMed search yields 168 papers using chorionic villous as of June 15, 2011.</ref> is a form of prenatal diagnosis done to determine chromosomal or genetic disorders in the fetus. It entails sampling of the chorionic villus (placental tissue) and testing it for chromosomal abnormalities, usually with FISH or PCR. CVS usually takes place at 10–12 weeks' gestation, earlier than amniocentesis or percutaneous umbilical cord blood sampling. It is the preferred technique before 15 weeks.<ref name=":0">Template:Cite journal</ref>

CVS was performed for the first time in Milan by Italian biologist Giuseppe Simoni, scientific director of Biocell Center, in 1983.<ref name="Lancet">Template:Cite journal</ref> Use as early as eight weeks in special circumstances has been described.<ref name="pmid12066086">Template:Cite journal</ref> It can be performed in a transcervical or transabdominal manner.<ref name=":0" /> Although this procedure is mostly associated with testing for Down syndrome, overall, CVS can detect more than 200 disorders.<ref>Template:MedlinePlusEncyclopedia</ref>

IndicationsEdit

Possible reasons for having a CVS can include:Template:Cn

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
Advanced maternal age (maternal age above 35). AMA is associated with increase risk of Down's syndrome and at age 35, risk is 1:400.Template:Citation needed Screening tests are usually carried out first before deciding if CVS should be done.

RisksEdit

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.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }} Page last reviewed: 06/08/2015</ref> 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).<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref>

Additionally, there is also mild risk of limb reduction defects associated with CVS, with the risk being higher the earlier the procedure is carried.<ref>Template:Cite journal</ref>

It is important after having CVS that the obstetrician follows the patient closely to ensure the patient does not develop infection.Template:Cn

Chorionic villi and stem cellsEdit

Recent studies have discovered that chorionic villi can be a rich source of fetal stem cells, multipotent mesenchymal stem cells.<ref name="wash_post">Template:Cite news</ref><ref name="nature">Template:Cite journal</ref><ref name="urlStem Cells - BiocellCenter">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

A potential benefit of using fetal stem cells over those obtained from embryos is that they side-step ethical 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.Template: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.<ref name="urlStem cells scientific updates - BiocellCenter">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

The first fetal stem cells bank in US is active in Boston, Massachusetts.<ref name="European Biotech Company Biocell Center Opens First U.S. Facility for Preservation of Amniotic Stem Cells in Medford, Massachusetts">Template:Cite news</ref><ref name="urlEuropes Biocell Center opens Medford office - Daily Business Update - The Boston Globe">Template:Cite news</ref><ref name="urlThe Ticker - BostonHerald.com">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref name="urlBiocell partner with largest New England's hospital group to preserve amniotic stem cell | PRNews">Template:Cite press release</ref>

LimitationsEdit

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.<ref name="Wapner">Template:Cite journal</ref> 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).<ref name=Wapner/> 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.Template:Citation needed

ReferencesEdit

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External linksEdit

Template:Obstetrical procedures Template:Pregnancy Template:Authority control