Which procedure involves obtaining fetal material from the chorion?

• A. Amniocentesis
• B. Preimplantation genetic diagnosis
• C. Chorionic villus sampling
• D. Karyotyping

Answer: (C)

Chorionic villus sampling is the correct procedure that involves obtaining fetal material from the chorion, which is the outermost layer of the fetal membranes. This procedure is typically performed between the 10th and 13th weeks of gestation and allows for the collection of chorionic villi, which contain fetal cells. These cells can then be analyzed for genetic abnormalities or chromosomal disorders.

The significance of chorionic villus sampling lies in its ability to provide early diagnostic information about genetic conditions, allowing expectant parents to make informed decisions. The chorion is a rich source of fetal DNA, making it ideal for such testing.

In contrast, amniocentesis involves obtaining amniotic fluid that surrounds the fetus, which contains fetal cells but does not involve the chorion directly. Preimplantation genetic diagnosis takes place before implantation of an embryo during in vitro fertilization and doesn't involve fetal material as it examines embryos. Karyotyping involves analyzing chromosomes from cells but is not a direct procedure for obtaining fetal material from the chorion itself. Thus, the specificity of chorionic villus sampling in obtaining chorionic tissue makes it the correct answer.