Diagnosis & Tests
Screening for Down syndrome is offered as a routine part of prenatal care. While a mother's age has usually been a factor in the decision to screen for Down syndrome, the American College of Obstetricians and Gynecologists now recommends offering various screening tests for Down syndrome to all pregnant women.
Screening tests offered during pregnancy include:
- Blood test—Typically, these are been offered around the 16th week of pregnancy to screen for Down syndrome, spina bifida and various other chromosomal disorders.
- First trimester combined test—For women who want an earlier risk assessment, this test is done in two steps from week 11 to week 13 of pregnancy. About 5 percent of women who undergo the first trimester combined test have a false-positive. The first trimester combined test includes an ultrasound to measure a specific region on the back of the baby’s neck, as well as blood tests.
- Full integrated testing—This is done in two parts during the first two trimesters of pregnancy. The results of the two parts (an ultrasound done during the first trimester and blood tests during the second) are combined to estimate the risk that a baby has Down syndrome. Only about 1 percent of women have a false-positive result with this type of testing.
If a screening test indicates a high risk of Down syndrome, a more invasive test may be used to determine whether the baby actually has Down syndrome.
Diagnostic tests that can identify Down syndrome include:
- Amniocentesis—A sample of the amniotic fluid surrounding the fetus is withdrawn through a needle inserted into the mother's uterus. This sample is used to analyze the chromosomes of the fetus. This test, which is usually performed after 15 weeks gestation, carries a 1 in 200 risk of miscarriage.
- Chorionic villus sampling (CVS)—Cells taken from a mother's placenta can be used to analyze the fetal chromosomes. This test, which is typically conducted between the 9th and 14th week of pregnancy, carries a 1 in 100 risk of miscarriage.
- Percutaneous umbilical blood sampling (PUBS)—In this test, blood is taken from a vein in the umbilical cord and examined for chromosomal defects. Doctors generally perform this test after 18 weeks of gestation. The test carries a greater risk of miscarriage than the above two tests and is generally only done when speed of diagnosis is essential.
Each of these three tests is 98 to 99 percent accurate in diagnosing Down syndrome before birth.
There are also diagnostic tests for newborns. After birth, the initial diagnosis of Down syndrome is often based on the baby's appearance. If a child displays some or all of the characteristics of Down syndrome, a doctor will normally order a test called a chromosomal karyotype. This test is an analysis of your child's chromosomes.
To obtain a karyotype, doctors draw a blood sample to examine the baby's cells. They use special tools to photograph the chromosomes and then group them by size, number, and shape. If there's an extra chromosome 21 present in all or some of the cells, the diagnosis is Down syndrome.
Another genetic test called fluorescent in situ hybridization (FISH) can apply similar principles and confirm a diagnosis in a shorter amount of time.
Early intervention for infants and children with Down syndrome can make a difference in realizing their potential abilities and in their quality of life.
Specialized programs, called early intervention programs, are available in most states. They vary from location to location, but they usually involve therapists and special educators whose goal is to help children develop motor skills, language, social skills and self-help skills.
Today people with Down syndrome live at home with their families and are active participants in the educational, vocational, social, and recreational activities of the community. They are integrated into the regular education system and take part in sports, camping, music, art programs and all the other activities of their communities.
In almost every community of the United States there are parent support groups and other community organizations directly involved in providing services to families of individuals with Down syndrome. For more information on support groups in Missouri and visit the community support group page of the Down Syndrome Association of Greater St. Louis.
Businesses are seeking young adults with Down syndrome for a variety of positions. They are being employed in small- and medium-sized offices: by banks, corporations, nursing homes, hotels and restaurants. They work in the music and entertainment industry, in clerical positions, childcare, the sports field and in the computer industry.
Research on Down syndrome is making great strides in identifying the genes on chromosome 21 that cause the characteristics of Down syndrome. Scientists now feel strongly that it will be possible to improve, correct or prevent many of the problems associated with Down syndrome in the future.