Prenatal diagnosis at 18 - 20 weeks of pregnancy can be performed using all of the following, except:
Prenatal diagnostic techniques for fetal abnormalities Chorionic villus sampling - done at First trimester(10-13th weeks) Amniocentesis - done at second trimester(16-18th weeks) Percutaneous umbilical blood sampling (cordocentesis) - done after 18 weeks. Non invasive Prenatal Test: Maternal serum is taken for evaluation of Down's syndrome & other chromosomal and genetic disorders. All pregnant female have cell free fetal DNA in their circulation which can be used to assess fetal karyotype. Source of cell free DNA is apoptosis of placental cells. This can be done anytime after 9 weeks
Amniotic fluid
Maternal blood
Chorionic villus sampling
Fetal blood
Diagnosis of Pregnancy