Prenatal Screening Flashcards
What is karyotyping
A cell undergoing mitosis. Homologous chromosomes are cut out and paired together based on size, shape and position of the centromere. This can be used to find out any missing or additional chromosomes. 3 x #21
Ultrasound
High frequency sound waves reflect off the fetus and translate to an image on a screen. Gives information regarding the size and position of the fetus. Can be used to identify certain abnormalities such as missing limbs, heart abnormalities..
Fetoscopy
Allows direct observation of a fetus. A slender tube containing a camera and a light is inserted into a small incision in the women’s abdomen. Gives a view of the fetus as well as allows procedures to be performed such as removing water from the brain or doing a fetal blood transfusion.
Amniocentesis
A long needle is inserted into the amniotic sack of a pregnant women (after 14 week)(very risky) amniotic fluid is removed. Fluid contains cells shed from the embryo. Can be karyotyped and then determine the gender and any missing or additional chromosomes. Usually for down syndrome ( common in age 40 women).
Chorionic Villus Sampling (C.V.S)
small piece of the chorionic membrane that surrounds the embryo is removed. These cells which are genetically identical to the embryo can be karyotyped and tested within one day. Done after 9 weeks pregnant.
Cell-free DNA prenatal screening
NON-INVASIVE. Analyzes fragments of cell-free DNA that represents the genetic profile of the fetus, which is derived from the placenta and is in the mother’s blood. This test can identify abnormal number of certain chromosomes. (levels of blood is checked) anything positive don’t trust it check with another method.
