**Core Concept**
Chorionic villous sampling (CVS) is a prenatal diagnostic test that involves taking a small sample of placental tissue for genetic analysis. This procedure is typically performed between 10 and 12 weeks of gestation and is used to detect chromosomal abnormalities, genetic disorders, and other fetal anomalies.

**Why the Correct Answer is Right**
Chorionic villous sampling is a valuable tool for diagnosing genetic conditions such as Down syndrome, Turner syndrome, and other chromosomal abnormalities. The procedure involves inserting a catheter through the cervix and into the placenta to collect a sample of chorionic villi, which are tiny finger-like projections of placental tissue. The sample is then analyzed for genetic material, allowing for the detection of abnormalities such as extra or missing chromosomes.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because CVS is not primarily used for detecting fetal infections such as CMV or toxoplasmosis. While CVS can incidentally detect some infections, it is not a reliable method for diagnosing these conditions.
**Option B:** This option is incorrect because CVS is not typically used for detecting fetal sex. Amniocentesis, another prenatal diagnostic test, is often used for this purpose.
**Option C:** This option is incorrect because CVS is not primarily used for detecting fetal anatomy. Ultrasound and other imaging modalities are more commonly used for this purpose.

**Clinical Pearl / High-Yield Fact**
CVS is a valuable tool for diagnosing genetic conditions, but it carries a small risk of miscarriage and other complications. It is essential to discuss the risks and benefits of CVS with patients to determine whether it is the best course of action for their individual situation.

**Correct Answer: D. Fetal anatomy.**