Down Syndrome - Exams and Tests

SYMPTOMS & TREATMENTS

Testing before becoming pregnant

You may want to consider genetic testing for Down syndrome if you are planning to become pregnant and you have a family history of the condition. Genetic testing can confirm whether you or your partner carry the translocation chromosome, which increases your risk for having a child with the translocation type of Down syndrome. But this kind of testing does not detect whether your child is more likely to have the trisomy 21 type, which accounts for most Down syndrome cases.

Genetic counseling can help you understand why genetic testing is done, what the results mean, and how the results may affect you and your family.

Screening during pregnancy

Screening does not diagnose Down syndrome but rather provides information about the likelihood that your fetus will have the condition. Screening tests include:

  • Fetal ultrasound and blood tests in the first trimester (combined screening). One advantage of combined screening is that it can be done earlier in your pregnancy than some other tests. An ultrasound image can show a greater-than-normal amount of fluid at the back of a fetus's neck. The skin fold thickness measurement estimates the distance between the surface of the skin and the neck bones (nuchal fold). The skin fold test may not be widely available, because only a specially trained provider can do it. A blood test checks the mother's levels of human chorionic gonadotropin (hCG) and pregnancy-associated plasma protein-A (PAPP-A).
  • Integrated screening. This screening involves both first and second trimester tests to predict the risk of having a child with Down syndrome. This test may not be available everywhere. It is one of the most accurate tests.5 The results are reported only after both sets of tests are finished. This can be cause for concern for women who would like to know test results early on.
  • Maternal serum triple or quadruple screen test. These are second trimester tests. The triple test (triple screen) checks the amounts of the following 3 substances in your blood:

The test is called a quadruple screen (quad screen) when a test for inhibin A is added. Inhibin A is a protein that is produced by the fetus and the placenta.

Click here to view a Decision Point.Should I have the maternal serum triple or quadruple test?

Screening tests for Down syndrome and other conditions require your consent. Some women find that knowing their chances of having a child with Down syndrome helps them to prepare for the possibility. Others are more comfortable going through their pregnancy without having this information.

The type of screening tests given, alone or in combination, depends on your goals and preferences. For example, when a mother is most concerned with screening accuracy and does not want to have amniocentesis, her doctor may recommend a combination of fetal ultrasound and blood test during the first trimester plus a triple or quad screen during the second trimester.

Diagnosis during pregnancy

A chromosomal analysis, called a karyotype test, can diagnose Down syndrome during pregnancy. A sample is taken directly from the fetus or placenta using one of the following techniques:

  • Amniocentesis. This usually is done at 15 to 18 weeks or later in your pregnancy. The liquid (amniotic fluid) that surrounds the fetus contains cells that have been shed by your developing baby. These cells can be checked for the number and size of chromosomes to see if there are any problems that put the baby at risk for certain conditions, such as Down syndrome. The test is done by inserting a needle through your abdomen into your uterus. A small amount of the amniotic fluid is collected and examined. Results of amniocentesis usually take about 2 weeks.
  • Chorionic villus sampling (CVS). This test is done earlier than amniocentesis, ideally between weeks 10 and 12 of your pregnancy. Chorionic villiClick here to see an illustration. are tiny finger-shaped growths found in the placenta. The genetic material in chorionic villus cells is identical to the genetic material in fetal cells. A biopsy of these cells can provide doctors with genetic information about your fetus. Doctors can then let you know whether your fetus is likely to have certain conditions, such as Down syndrome, that can develop from chromosomes that are not normal. The chorionic villus sample is usually collected through the mother's vagina. The doctor inserts a speculum to gently spread apart the vaginal walls. Then a tube (catheter) is guided through the cervix to the placenta using ultrasound. When the tube is correctly placed, a sample of chorionic villus cells is collected. Less often, the sample of chorionic villus cells is collected by inserting a needle through the abdomen into the woman's uterus. Results of CVS are usually available within several days.

Risks, such as miscarriage, are associated with amniocentesis and CVS. It is always your choice whether to have your fetus tested for Down syndrome. A diagnosis of Down syndrome made early in fetal development allows you the option of terminating your pregnancy. If you choose to continue the pregnancy, early awareness can help you prepare emotionally and plan for the special needs of your child. A genetic counselor can help you during this process.

Click here to view a Decision Point.Should I have chorionic villus sampling?
Click here to view a Decision Point.Should I have an amniocentesis?

If a fetus is diagnosed with Down syndrome, a doctor may recommend fetal echocardiography to screen for heart defects and fetal ultrasound to help detect digestive system problems. Any suspected defects will be further investigated after birth.

Diagnosis after your baby is born

If Down syndrome was not diagnosed before birth, a baby's physical features at birth often give doctors a clear sense of whether the child has Down syndrome. But traits can be subtle in a newborn, depending on the type of Down syndrome that he or she has. In general, doctors can often make a diagnosis by doing a physical exam.

A newborn will also have a blood sample taken for chromosomal analysis to confirm the diagnosis. It may take 2 to 3 weeks to get the complete results of this test.

Exams and tests at birth and throughout life

Screening guidelines according to age were developed by the American Academy of Pediatrics and the Down Syndrome Medical Interest Group for people who have Down syndrome. Doctors screen for common problems seen in people with Down syndrome, such as heart, hearing, or vision problems.

What to think about

One of the greatest difficulties parents face is finding a way to tell family members and friends about their child's condition. If you do not learn that your baby has Down syndrome until after he or she is born, you will have little time to absorb the information before you need to answer questions from excited family and friends who are eager for news. The best approach may be to simply state the facts, such as, "Our baby was diagnosed with Down syndrome." If you are not ready to talk about your child's condition beyond that, say so. You may feel able to tell only one or two people. If this is the case, consider asking them to share the news with others. Of course, there is no right or wrong way to tell people. Know that there are resources to help you.

Waiting for a formal diagnosis can be stressful. It can take 2 to 3 weeks to get the test results. Try to focus on caring and bonding with your newborn and getting the help you need. Your doctor or local hospital can refer you to community resources to help you learn what to expect and how to care for your baby with Down syndrome. Support groups may be especially helpful in learning not only about the challenges of having a child with Down syndrome but also the joys and positive experiences other parents have had. You may also find it helpful to meet and talk with families who have a child with Down syndrome. Talking with religious or spiritual leaders, genetic counselors, or loved ones may help you deal with difficult emotions.

Early detection

Testing for Down syndrome during pregnancy (prenatal testing), which requires your consent, may be recommended if you:

  • Want to know for sure if your fetus has Down syndrome.
  • Have a family history of Down syndrome or your partner has a family history of Down syndrome.
  • Know that you or your partner carry the translocation type of Down syndrome.

Prenatal testing for a formal diagnosis of Down syndrome requires karyotyping. The sample used for this testing is taken during amniocentesis or chorionic villus sampling.

Genetic counseling offers a lot of information and help for couples who are planning to become pregnant. For example, couples who have a child with Down syndrome can use genetic counseling to help determine their risk for having another child with the condition.

By: Healthwise StaffLast Revised: February 10, 2010
Medical Review: Michael J. Sexton, MD - Pediatrics
Siobhan M. Dolan, MD, MPH - Reproductive Genetics
David Smith, MD - Family Medicine

© 1995-2011 Healthwise, Incorporated. Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated. This information does not replace the advice of a doctor. Healthwise, Incorporated disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Terms of Use. How this information was developed to help you make better health decisions.

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