How can chromosomal abnormalities of an unborn baby be diagnosed during pregnancy?
1. Chorionic Villus Sampling (CVS):
- CVS is performed between 10 and 13 weeks of pregnancy.
- A small sample of chorionic villi, which are finger-like projections of the placenta, is collected through the cervix or abdomen.
- The sample is analyzed to detect chromosomal abnormalities.
2. Amniocentesis:
- Amniocentesis is usually performed between 15 and 20 weeks of pregnancy.
- A thin needle is inserted into the amniotic sac to withdraw a small amount of amniotic fluid.
- The fluid contains fetal cells, which are then analyzed for chromosomal abnormalities.
3. Non-Invasive Prenatal Testing (NIPT):
- NIPT, also known as cell-free DNA testing, can be performed as early as 10 weeks of pregnancy.
- A blood sample is taken from the mother to analyze fragments of fetal DNA circulating in her bloodstream.
- NIPT can screen for common chromosomal abnormalities, including trisomy 21 (Down syndrome), trisomy 18 (Edwards syndrome), and trisomy 13 (Patau syndrome).
4. Ultrasound:
- Ultrasound imaging, performed throughout pregnancy, can provide indirect indications of potential chromosomal abnormalities.
- Certain physical markers or anomalies observed during ultrasound scans may suggest the need for further genetic testing.
5. Preimplantation Genetic Testing (PGT):
- PGT is performed during in vitro fertilization (IVF) procedures.
- It involves the genetic analysis of embryos created in the lab before implantation into the uterus.
- PGT can identify chromosomal abnormalities and select embryos that are free from specific genetic conditions.
These prenatal tests are typically recommended based on a woman's age, family history, and specific risk factors. Genetic counseling is an essential component of prenatal care, as it helps expectant parents understand the risks, benefits, and limitations of available testing options.