They are used to test the fetus’ for general health and for testing embryos before implantation in In Vitro Fertilisation (IVF) procedures.<\/p>\n\n\n\n After DNA isolation, karyotyping can be done by CGH and FISH(karyotyping and karyotyping methods are discussed in detail in the Cytogenetics: Cytogenetic Methods lesson)<\/em>.<\/p>\n\n\n\n <\/p>\n<\/span>Prenatal screening vs Prenatal diagnosis<\/h4>\n<\/span>\n\n\n
<\/td> Prenatal Screening<\/td> Prenatal Diagnosis<\/td><\/tr> 1. <\/td> Also known as Non-Invasive Prenatal testing, it is used to identify women who have a high chance to have babies with chromosomal abnormalities.<\/td> Also known as Invasive Prenatal Testing, it is used to confirm the results of the prenatal screening<\/td><\/tr> 2.<\/td> Involves non-invasive methods(isolating fetal cells\/DNA from maternal blood\/serum\/plasma). Lymphocytes, red blood cells and cell-free DNA can be gotten from the mother.<\/td> Involves invasive methods(entering the uterus or placenta to collect sample cells)<\/td><\/tr> 3. <\/td> Those with a negative test do not have to undergo any further testing, while those with a positive test will go for a prenatal diagnostic test.<\/td> Confirmatory test for prenatal screening to give a diagnosis for the developmental or chromosomal abnormality of the fetus<\/td><\/tr> 4.<\/td> Methods used here involve measurement of maternal serum markers (such as AFP;alpha-fetoprotein and HCG; human chorionic gonadotropin)and ultrasound.<\/td> Methods used here are Amniocentesis and Chorionic Villus Sampling(CVS)<\/td><\/tr> 5.<\/td> Can be performed in the first and\/or second trimesters<\/td> Amniocentesis is performed between weeks 15 and 20 and Chorionic Villus Sampling(CVS) is performed between weeks 11 and 14.<\/td><\/tr> 6.<\/td> there is no increased risk of spontaneous abortions with these methods<\/td> there is an increased risk of spontaneous abortions with these methods<\/td><\/tr><\/tbody><\/table>