Trisomy 21 - Down Syndrome

How is the condition diagnosed?

Down syndrome may be suspected at birth when certain physical features or defects are present. A chromosome analysis, however, confirms the diagnosis.

There are also tests that screen for Down syndrome during pregnancy. A blood test known as the triple screen measures the levels of certain chemicals in a pregnant woman's blood. These chemicals are estriol, human chorionic gonadotropin, and alpha-fetoprotein. When the chemicals are out of balance, there is a risk that the fetus has Down syndrome.

Other tests can be ordered to confirm the diagnosis of Down syndrome. These tests analyze the chromosomes of tissue taken from the fetus. These tests include chorionic villus sampling and amniocentesis.