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Chorionic villus sampling is a test that women can have during early pregnancy to look for certain fetal problems. This test is most often performed when the father or the mother have a family history of a genetic disorder. It is also sometimes performed on women over the age of 35 years of age due to the increased risk of giving birth to a child with a chromosome defect.
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Why is this Genetic Testing Done?
This test is done to look for a variety of genetic issues and factors, including:
- Family genetic disorders
- When Rh sensitization occurs this can be done to determine the baby's blood type
- Find chromosomal birth defects (specifically women over 35)
- If the parent may have a sex-linked disorder this can be done to determine the sex of the baby
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Who Should Have this Testing?
Chorionic villus sampling may be a good choice if:
- The patient is older than 35 years of age
- Previous testing suggesting the possibility of the fetus having Down syndrome
- Either or both of the parents having the chance of passing down a genetic disorder
- Already having a child with a chromosome defect such as Down syndrome
- Having a medical need to know the sex of the baby
- An ultrasound suggested the fetus could have a birth defect
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How is this Genetic Testing Done?
During this procedure a small piece of chorionic villi (placenta tissue) from the uterus will be removed to screen a baby for possible genetic defects during early pregnancy. This procedure can be done transabdominal (through the abdomen) or transcervical (through the cervix). Ultrasound is used to determine how big the gestational sac is, the position of the uterus, and the placenta's position within the uterus. The area will be thoroughly cleaned with an antiseptic prior to the procedure. During the transcervical procedure, a thin plastic tube is inserted through the vagina and cervix to the placenta and then a sample is taken. During the transabdominal procedure, a needle is inserted into the placenta through the abdomen and uterus and a sample is drawn into the syringe.
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What do the Results Mean?
A normal result indicates that no signs of genetic defects were found. However, some genetic defects could be missed by this test.
An abnormal result could indicate one of more than 200 different genetic disorders, including:
- Down syndrome
- Tay-Sachs disease
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What are the Possible Risks?
All patients should be aware of the possible complications. They should also be aware of the signs and symptoms of the possible complications.
Possible complications can include:
- Rupture of membranes
- Rh incompatibility in the mother
Signs of complications include:
- Excessive vaginal discharge
- Excessive bleeding
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WebMD. (2008). Chorionic Villus Sampling. Retrieved on July 23, 2010 from WebMD: http://www.webmd.com/baby/chorionic-villus-sampling-cvs
Medline Plus. (2010). Chorionic Villus Sampling. Retrieved on July 23, 2010 from Medline Plus: http://www.nlm.nih.gov/medlineplus/ency/article/003406.htm