Overview of Chorionic Villus Sampling
Chorionic Villus Sampling (CVS) is a prenatal diagnostic procedure that involves obtaining a sample of chorionic villi from the placenta for genetic analysis. It helps in diagnosing chromosomal and genetic conditions early in pregnancy.
Procedure
- Timing:
CVS is typically performed between 10 and 13 weeks of pregnancy. It is done earlier than amniocentesis, making it a useful option for early diagnosis. - Preparation:
An ultrasound is used to guide the procedure and to locate the placenta and the fetus.

Uses
- Genetic Testing: To diagnose chromosomal abnormalities such as Down syndrome (trisomy 21), trisomy 18, and other genetic disorders.
- Karyotyping: To analyze the fetal chromosomes for structural abnormalities.
- Genetic Disorders: To test for specific genetic disorders if there is a known risk due to family history or previous genetic testing.
Advantages
- Early Detection: CVS can be performed earlier in pregnancy compared to amniocentesis, allowing for earlier diagnosis and decision-making.
- Accurate Results: Provides accurate results for genetic and chromosomal conditions, similar to amniocentesis.
- Diagnostic Capability: Can diagnose a wide range of genetic disorders early in the pregnancy.
Risks and Considerations
- Miscarriage: The risk of miscarriage following CVS is estimated to be between 1 in 100 and 1 in 200, which is higher than the risk associated with amniocentesis. However, this risk is still relatively low.
- Infection: There is a small risk of infection at the catheter or needle insertion site.
- Bleeding and Cramping: Some bleeding or cramping can occur after the procedure, but these symptoms are usually mild and resolve on their own.
- Needle/Catheter Injury: There is a small risk of injury to the fetus or placenta, although this is rare with careful technique.
Aftercare and Follow-Up
- Monitoring: The mother and fetus may be monitored for any complications following the procedure.
- Results: Results from CVS typically take about 1-2 weeks to return. The sample is analyzed for chromosomal abnormalities and genetic conditions.
- Counseling: Genetic counseling is often provided to discuss the results, their implications, and potential options based on the findings.
Alternatives
- Amniocentesis: A similar diagnostic procedure that is performed later in pregnancy (between 15 and 20 weeks) and involves sampling amniotic fluid.
- Non-Invasive Prenatal Testing (NIPT): A blood test analyzing fetal DNA from the mother’s blood. NIPT is used for screening rather than diagnostic purposes and can be performed as early as 10 weeks of pregnancy.
Summary
Chorionic Villus Sampling (CVS) is a valuable tool for early diagnosis of genetic and chromosomal conditions in pregnancy. While it carries some risks, it provides critical information that can help guide decisions about pregnancy management and care. If CVS is recommended, it’s important to discuss the benefits, risks, and implications with a healthcare provider or genetic counselor to make an informed decision.

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