The two most effective and most used techniques for genetic screening
are amniocentesis and ultrasounds.
Amniocentesis is when the doctors use a syringe to take fluid from a sac
that surrounds the fetus. This amniotic fluid contains cells from the fetus, by putting special stains in these cells the
tiny chromosomes can be seen. Microscopic examination can now be done. There is a camera mounted on the microscope that physicians
use to take pictures of the chromosomes. The chromosomes in the pictures are arranged into a karyotype chart. By comparing
the homologous chromosomes the exact disorder can be determined. If there is 47 chromosomes, that would indicate a non-disjunction
disorder.
Ultrasound is mainly used to determine the sex of the baby. It can also be
used to see the position of the fetus in the uterus. It allows genetic conditions to be detected, diagnosed and sometimes
treated. The time that this type of screening is done, is crucial. Women are often offered a scan at twenty weeks and sometimes
even at twelve. At these times the baby is usually seen clearly. Between the eighteenth and twentieth weeks it is hard to
scan because of the position the fetus is in. If the ultrasound detects a risk a diagnosic test can be done to examine the
DNA, chromosomes, protien or blood cells to figure out whether or not the fetus will have a disorder when it is born.
