Chorionic Villus Sampling (CVS)

Chorionic villus sampling (CVS) is a prenatal diagnostic test that involves removing a small sample of cells from the placenta, specifically from the chorionic villi, to detect 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 detect genetic disorders or chromosomal abnormalities in the fetus, 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 detection 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. If a genetic disorder or chromosomal abnormality is detected, the patient will be counseled about the diagnosis and options for further testing or management.

Alternatives

Alternative prenatal diagnostic tests include:

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