Chorionic Villus Sampling (CVS)

Chorionic villus sampling (CVS) is a prenatal test that involves removing a small sample of cells from the placenta, specifically from the chorionic villi, to diagnose certain genetic disorders or chromosomal abnormalities in the fetus.

Procedure

The CVS procedure typically takes place between 10 and 12 weeks of pregnancy. There are two methods of performing CVS:

• Transcervical CVS: A catheter is inserted through the cervix and guided to the placenta using ultrasound. The catheter is then used to remove a small sample of chorionic villi.
• Transabdominal CVS: A needle is inserted through the abdomen and guided to the placenta using ultrasound. The needle is then used to remove a small sample of chorionic villi.

Purpose

The primary purpose of CVS is to diagnose genetic disorders or chromosomal abnormalities, such as:

• Down syndrome (trisomy 21)
• Cystic fibrosis
• Sickle cell disease
• Tay-Sachs disease
• Other genetic disorders

Risks and Complications

As with any invasive medical procedure, there are risks and complications associated with CVS, including:

• Miscarriage (less than 1% risk)
• Infection
• Bleeding or spotting
• Rh sensitization (if the mother is Rh-negative)

Benefits

The benefits of CVS include:

• Early diagnosis of genetic disorders or chromosomal abnormalities, allowing for informed decision-making about the pregnancy
• A high degree of accuracy (greater than 99%) in detecting certain genetic disorders
• The ability to perform the test earlier in pregnancy compared to amniocentesis (typically performed between 15 and 20 weeks)

Results

The results of CVS are typically available within 1-2 weeks. The test can detect:

• Chromosomal abnormalities, such as aneuploidy (having an abnormal number of chromosomes)
• Genetic disorders caused by mutations in specific genes

Alternatives

Alternative prenatal tests include:

• Amniocentesis
• Non-invasive prenatal testing (NIPT)
• Maternal serum screening (MSS)

Conclusion

Chorionic villus sampling (CVS) is a valuable prenatal test for detecting genetic disorders or chromosomal abnormalities in the fetus. While it carries some risks and complications, the benefits of early diagnosis and high accuracy make it an important tool for informed decision-making about the pregnancy.

Frequently Asked Questions (FAQs)

What is Chorionic villus sampling (CVS)?
A prenatal test that involves removing a sample of cells from the placenta.

Why is CVS performed?
To detect genetic disorders or chromosomal abnormalities in the fetus.

When is CVS typically performed?
Between 10 and 12 weeks of pregnancy, sometimes up to 13 weeks.

How is CVS performed?
Through the abdomen or cervix, using a needle or catheter guided by ultrasound.

What are the risks associated with CVS?
Miscarriage, infection, and bleeding, among others, although generally considered low.

Is CVS more accurate than other prenatal tests?
Generally considered highly accurate, but not 100%, for detecting certain genetic disorders.

Can CVS detect all genetic disorders?
No, it cannot detect all genetic disorders, only those related to chromosomal abnormalities or specific genetic conditions.

How long does it usually take to get CVS results?
Typically 1-2 weeks, depending on the laboratory and type of test.

Is CVS covered by insurance?
Often covered, but coverage varies depending on the insurance provider and individual policy.

Are there alternative prenatal tests to CVS?
Yes, such as amniocentesis, non-invasive prenatal testing (NIPT), and maternal serum screening.