- Indications: CVS is typically recommended for pregnant individuals who are at increased risk of having a baby with certain genetic conditions or chromosomal abnormalities. This includes individuals with:
- Advanced maternal age (typically 35 years or older at the time of delivery).
- Positive results on prenatal screening tests indicating an increased risk of chromosomal abnormalities.
- A family history of genetic disorders or chromosomal abnormalities.
- Previous pregnancies with genetic conditions or chromosomal abnormalities.
- Abnormal findings on ultrasound examinations, such as structural abnormalities or markers suggestive of chromosomal abnormalities.
- Procedure: CVS is usually performed between 10 and 13 weeks of pregnancy, although it can be done earlier in some cases. The procedure is typically done in an outpatient setting, such as a doctor's office or prenatal testing center, and involves the following steps:
- The pregnant individual lies on their back while an ultrasound is used to visualize the fetus and placenta.
- The healthcare provider cleans the mother's abdomen with an antiseptic solution and applies local anesthesia to numb the skin.
- Using ultrasound guidance, a thin tube or needle is inserted through the mother's abdominal wall and into the placenta.
- A small sample of chorionic villi is aspirated or extracted from the placenta using suction or a biopsy forceps.
- The sampled chorionic villi are collected in a sterile container and sent to a laboratory for analysis.
- Analysis: The collected chorionic villi contain fetal cells, including cells from the developing embryo's outer layer (trophoblast cells), which can be cultured and analyzed to obtain genetic information. The laboratory can perform various tests on the cells, including:
- Chromosome analysis (karyotyping) to detect numerical and structural chromosomal abnormalities.
- DNA analysis for specific genetic disorders or mutations.
- Biochemical analysis to assess levels of certain substances associated with metabolic disorders.
- Risks and Complications: CVS is generally considered a safe procedure, but it carries a small risk of complications, including:
- Risk of miscarriage: The risk of miscarriage associated with CVS is estimated to be about 1 in 100 (1%).
- Infection: There is a small risk of infection at the needle insertion site or within the uterus.
- Bleeding: CVS may cause minor bleeding or spotting from the needle insertion site.
- Leakage of amniotic fluid: In rare cases, CVS may cause leakage of amniotic fluid, which usually resolves on its own but can sometimes lead to complications.
- Counseling and Informed Consent: Before undergoing CVS, pregnant individuals receive counseling to understand the benefits, risks, and limitations of the procedure. Informed consent is obtained, allowing individuals to make an informed decision about whether to proceed with the test based on their personal circumstances and preferences.
CVS provides valuable diagnostic information that can help pregnant individuals and healthcare providers make informed decisions about pregnancy management, including options for prenatal care, pregnancy termination, and preparation for the birth of a child with special medical needs. However, it's important to weigh the potential benefits of CVS against the risks and consider individual circumstances and preferences when deciding whether to undergo the procedure.
