How is Down Syndrome Diagnosed?
It is imperative for families who are at risk of having a child with Down Syndrome undergo screening before the birth of the child. This is more important in females who get pregnant after the age of 35 years as there is more risk of the child developing Down Syndrome in females of this age group who get pregnant. Screenings are done to estimate the chances that the fetus will have of having down syndrome.
Screenings along with laboratory tests more or less confirm whether the fetus has Down Syndrome or not. These diagnostic tests are performed within the uterus and come with an increased risk of harming the fetus and even miscarriage or preterm labor, although they are very accurate in detecting whether the fetus has this condition or not.
Some of the screening tests done to diagnose if the fetus has Down Syndrome are:
Nuchal Translucency Testing: This test is done in the first trimester within 11-14 weeks of pregnancy. In this test, an ultrasound is done to measure the clear space in tissues behind the neck of the baby.
Quadruple Screening: This is done between the 15th and 18th week of pregnancy and measures the quantities of various substances that are present in the blood of the mother.
Integrated Screening: This screenings combines the screenings and blood tests of the first trimester with second trimester screenings and blood tests.
Fetal DNA Test: This is a blood test that is done to analyze fetal DNA which is present in the mother's blood and is also called as cell-free DNA testing
Genetic Ultrasound: This is done between the 18th and the 20th week of pregnancy in which there is a detailed ultrasound done along with complete blood tests.
Any abnormality in any of the screenings mentioned above raises suspicion for the baby having Down Syndrome and further diagnostic studies are advised. These diagnostic studies are:
Chorionic Villus Sampling: This test is done between 8th and 12th week of the pregnancy. In this test, a sample of the placenta is taken through a needle that is inserted into the cervix
Amniocentesis: This is done between 15th and 20th week of pregnancy and this test involves analysis of the amniotic fluid which is taken in a small amount through a needle from the abdomen
Percutaneous Umbilical Blood Sampling: This is done mostly in the third trimester or after 20th week of pregnancy and involves analysis of the blood from the umbilical cord which is taken in a small amount through a needle inserted into the abdomen
The results of these tests virtually confirm whether a baby is suffering from Down Syndrome even before it is born.
Down Syndrome can also be diagnosed after the birth of the baby just by looking at the physical features of the baby which will clearly show whether the child has Down Syndrome or not.
Can Down Syndrome be Prevented?
Down Syndrome is a condition which cannot be prevented but what can be done is if an individual has someone in the family with a known case of Down Syndrome or if the individual is considered to be at high risk candidate then a genetic counseling is advised before the female gets pregnant so as to have an idea as to the chances of the offspring having Down Syndrome.