Dangers of Chorionic Villus Sampling

Chorionic Villus Sampling is an alternative to Amniocentesis that can be used earlier in the pregnancy, usually between 10 and 13 weeks. Amniocentesis is usually performed between 15 and 18 weeks, or in third trimester to check for lung maturity or infection. Chorionic villus sampling tests for chromosomal abnormalities and genetic disorders, although it cannot detect neural tube defects. An ultrasound guides a thin catheter through the cervix to the placenta. The chorionic villi cells are gently suctioned into the catheter. This is the most common method. But an alternative procedure involves inserting a long thin needle through the mother’s abdomen and sampling the villi. Chorionic villus sampling carries a risk of miscarriage of one 1-2%, up to as high as 7.6%, slightly higher than amniocentesis.

Possible risks include miscarriage, Rh sensitization, infection, damage to the embryo, cervical lacerations, leakage of amniotic fluid, severe cramps, and limb reduction defects in the fetus, although there is disagreement as to the amount of risk for the latter. It is recommended that women with an active infection, women who care carrying twins, and women who have experienced vaginal bleeding during the pregnancy should not undergo this procedure. Also, women who have fibroids or a tilted uterus would not be candidates for transcervical sampling.

Whether or not disturbing the placenta is a good idea is questionable. DES daughters or older women who would normally be at risk for a loose cervix might not want to risk tampering with the cervix. The risks are the reason that CVS is not a common test.

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About Chorionic Villus Sampling, Emory University School of Medicine, 2008.

Understanding Diagnostic Tests in the Childbearing Year, 7th Edition, Anne Frye CPM, 2017.