Question

A 36-year-old woman requests prenatal diagnosis. She is healthy and excited about finally getting pregnant. She is interested in genetic counseling and asks about the advantages of chorionic villus sampling versus amniocentesis. Which of the following is true when chorionic villus sampling is compared to amniocentesis?

1) Reduced post-procedure loss rate
2) Performed earlier
3) More likely to obtain an adequate sample
4) Lower rate of procedure related birth defects
5) Performed in isoimmunized pregnancies

Answer 1

Chorionic villus sampling (CVS) and amniocentesis are prenatal diagnostic tests used to detect genetic abnormalities. CVS can be performed earlier and has a higher likelihood of obtaining an adequate sample, but carries a slightly higher risk of procedure-related miscarriage.

Step-by-step explanation:

Chorionic villus sampling (CVS) and amniocentesis are both prenatal diagnostic tests used to detect genetic abnormalities in a developing fetus. When comparing the two, the following statements are true:

1. Performed earlier: CVS can be performed between 10-13 weeks of pregnancy, while amniocentesis is typically done between 15-20 weeks.
2. More likely to obtain an adequate sample: CVS involves obtaining a small piece of tissue from the placenta, which contains the same genetic information as the fetus. This tissue can be readily tested, increasing the likelihood of obtaining an adequate sample.
3. Lower rate of procedure-related birth defects: CVS carries a slightly higher risk of procedure-related miscarriage compared to amniocentesis.