How early in pregnancy can you detect down syndrome
Down syndrome - Diagnosis and treatment
Diagnosis
The American College of Obstetricians and Gynecologists recommends offering the option of screening tests and diagnostic tests for Down syndrome to all pregnant women, regardless of age.
- Screening tests can indicate the likelihood or chances that a mother is carrying a baby with Down syndrome. But these tests can't tell for sure or diagnose whether the baby has Down syndrome.
- Diagnostic tests can identify or diagnose whether your baby has Down syndrome.
Your health care provider can discuss the types of tests, advantages and disadvantages, benefits and risks, and the meaning of your results. If appropriate, your provider may recommend that you talk to a genetics counselor.
Screening tests during pregnancy
Screening for Down syndrome is offered as a routine part of prenatal care. Although screening tests can only identify your risk of carrying a baby with Down syndrome, they can help you make decisions about more-specific diagnostic tests.
Screening tests include the first trimester combined test and the integrated screening test.
The first trimester combined test
The first trimester combined test, which is done in two steps, includes:
- Blood test. This blood test measures the levels of pregnancy-associated plasma protein-A (PAPP-A) and the pregnancy hormone known as human chorionic gonadotropin (HCG). Abnormal levels of PAPP-A and HCG may indicate a problem with the baby.
- Nuchal translucency test. During this test, an ultrasound is used to measure a specific area on the back of your baby's neck. This is known as a nuchal translucency screening test. When abnormalities are present, more fluid than usual tends to collect in this neck tissue.
Using your age and the results of the blood test and the ultrasound, your doctor or genetic counselor can estimate your risk of having a baby with Down syndrome.
Integrated screening test
The integrated screening test is done in two parts during the first and second trimesters of pregnancy.
The results are combined to estimate the risk that your baby has Down syndrome.
- First trimester. Part one includes a blood test to measure PAPP-A and an ultrasound to measure nuchal translucency.
- Second trimester. The quad screen measures your blood level of four pregnancy-associated substances: alpha fetoprotein, estriol, HCG and inhibin A.
Diagnostic tests during pregnancy
If your screening test results are positive or worrisome, or you're at high risk of having a baby with Down syndrome, you might consider more testing to confirm the diagnosis. Your health care provider can help you weigh the pros and cons of these tests.
Diagnostic tests that can identify Down syndrome include:
- Chorionic villus sampling (CVS). In CVS, cells are taken from the placenta and used to analyze the fetal chromosomes. This test is typically performed in the first trimester, between 10 and 13 weeks of pregnancy.
The risk of pregnancy loss (miscarriage) from a CVS is very low. - Amniocentesis. A sample of the amniotic fluid surrounding the fetus is withdrawn through a needle inserted into the mother's uterus. This sample is then used to analyze the chromosomes of the fetus. Doctors usually perform this test in the second trimester, after 15 weeks of pregnancy. This test also carries a very low risk of miscarriage.
Preimplantation genetic diagnosis is an option for couples undergoing in vitro fertilization who are at increased risk of passing along certain genetic conditions. The embryo is tested for genetic abnormalities before it's implanted in the womb.
Diagnostic tests for newborns
After birth, the initial diagnosis of Down syndrome is often based on the baby's appearance. But the features associated with Down syndrome can be found in babies without Down syndrome, so your health care provider will likely order a test called a chromosomal karyotype to confirm diagnosis.
Using a sample of blood, this test analyzes your child's chromosomes. If there's an extra chromosome 21 in all or some cells, the diagnosis is Down syndrome.
More Information
- Amniocentesis
- Chorionic villus sampling
- Cordocentesis
- Genetic testing
- Ultrasound
Treatment
Early intervention for infants and children with Down syndrome can make a major difference in improving their quality of life. Because each child with Down syndrome is unique, treatment will depend on individual needs. Also, different stages of life may require different services.
Team care
If your child has Down syndrome, you'll likely rely on a team of specialists that can provide medical care and help him or her develop skills as fully as possible. Depending on your child's particular needs, your team may include some of these experts:
- Primary care pediatrician to coordinate and provide routine childhood care
- Pediatric cardiologist
- Pediatric gastroenterologist
- Pediatric endocrinologist
- Developmental pediatrician
- Pediatric neurologist
- Pediatric ear, nose and throat (ENT) specialist
- Pediatric eye doctor (ophthalmologist)
- Audiologist
- Speech pathologist
- Physical therapist
- Occupational therapist
You'll need to make important decisions about your child's treatment and education.
Build a team of health care providers, teachers and therapists you trust. These professionals can help evaluate the resources in your area and explain state and federal programs for children and adults with disabilities.
Request an Appointment at Mayo Clinic
Coping and support
When you learn your child has Down syndrome, you may experience a range of emotions, including anger, fear, worry and sorrow. You may not know what to expect, and you may worry about your ability to care for a child with a disability. The best antidote for fear and worry is information and support.
Consider these steps to prepare yourself and to care for your child:
- Ask your health care provider about early intervention programs in your area. Available in most states, these special programs offer infants and young children with Down syndrome stimulation at an early age (typically until age 3) to help develop motor, language, social and self-help skills.
- Learn about educational options for school.
Depending on your child's needs, that may mean attending regular classes (mainstreaming), special education classes or both. With your health care team's recommendations, work with the school to understand and choose appropriate options. - Seek out other families who are dealing with the same issues. Most communities have support groups for parents of children with Down syndrome. You can also find internet support groups. Family and friends can also be a source of understanding and support.
- Participate in social and leisure activities. Take time for family outings and look in your community for social activities such as park district programs, sports teams or ballet classes. Although some adaptations may be required, children and adults with Down syndrome can enjoy social and leisure activities.
- Encourage independence. Your child's abilities may be different from other children's abilities, but with your support and some practice your child may be able to perform tasks such as packing lunch, managing hygiene and dressing, and doing light cooking and laundry.
- Prepare for the transition to adulthood. Opportunities for living, working, and social and leisure activities can be explored before your child leaves school. Community living or group homes, and community employment, day programs or workshops after high school require some advance planning. Ask about opportunities and support in your area.
Expect a bright future. Most people with Down syndrome live with their families or independently, go to mainstream schools, read and write, participate in the community, and have jobs. People with Down syndrome can live fulfilling lives.
By Mayo Clinic Staff
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Prenatal Testing for Down Syndrome | Patient Education
Down syndrome is a genetic condition caused by extra genes from the 21st chromosome. It results in certain characteristics, including some degree of cognitive disability and other developmental delays. Common physical traits include an upward slant of the eyes; flattened bridge of the nose; single, deep crease on the palm of the hand; and decreased muscle tone.
A child with Down syndrome, however, may not have all these traits.
The incidence of Down syndrome in the United States is about 1 in 1,000 births. There is no association between Down syndrome and culture, ethnic group, socioeconomic status or geographic region.
Age-Related Risks
Generally, the chance of having a Down syndrome birth is related to the mother's age. Under age 25, the odds of having a child with Down syndrome are about 1 in 1,400. At age 35, the odds are about 1 in 350. At age 40, the odds are about 1 in 100.
Causes of Down Syndrome
There are three causes of Down syndrome:
Trisomy 21
An estimated 95 percent of people with Down syndrome have trisomy 21, meaning they have three number 21 chromosomes instead of two. We normally have 23 pairs of chromosomes, each made up of genes. During the formation of the egg and the sperm, a woman's or a man's pair of chromosomes normally split so that only one chromosome is in each egg or sperm.
In trisomy 21, the 21st chromosome pair does not split and a double dose goes to the egg or sperm. An estimated 95 to 97 percent of the extra chromosome is of maternal origin.
Translocation
Translocation occurs in about 3 to 4 percent of people with Down syndrome. In this type, an extra part of the 21st chromosome gets stuck onto another chromosome. In about half of these situations, one parent carries the extra 21st chromosome material in a "balanced" or hidden form.
Mosaicism
In mosaicism, the person with Down syndrome has an extra 21st chromosome in some of the cells but not all of them. The other cells have the usual pair of 21st chromosomes. About 1 to 2 percent of people with Down syndrome have this type.
Prenatal Testing
Screening tests can identify women at increased risk of having a baby with Down syndrome. These tests have no risks of miscarriage, but can't determine with certainty whether a fetus is affected. Diagnostic tests, on the other hand, are extremely accurate at identifying certain abnormalities in the fetus, but carry a small — generally less than 1 percent — risk of miscarriage.
We offer options for both screening and diagnostic testing.
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Screening Tests
Sequential Integrated Screening — Sequential integrated screening is offered to all pregnant women by the state of California. This non-invasive screening is performed in two steps.
In the first step, which is performed between 10 and 14 weeks of pregnancy, a blood sample is taken from the mother and a nuchal translucency ultrasound is performed to measure the amount of fluid at the back of the baby's neck. If the blood test is scheduled prior to the ultrasound, we can provide the results at the end of the ultrasound appointment. The results of the blood test, the nuchal translucency measurement and the mother's age are used to estimate the risk for Down syndrome and trisomy 18.
The second step is a maternal blood test between 15 to 20 weeks of pregnancy. When the results of this blood test are combined with the results from the first trimester blood test and nuchal translucency ultrasound, the detection rate for Down syndrome increases.
This test also provides a personal risk assessment for having a fetus with trisomy 18, Smith-Lemli-Opitz syndrome, an open neural tube defect or an abdominal wall defect.
Diagnostic Tests
Amniocentesis, chorionic villus sampling (CVS) and ultrasound are the three primary procedures for diagnostic testing.
Amniocentesis — Amniocentesis is used most commonly to identify chromosomal problems such as Down syndrome. When the fetus is known to be at risk, it can detect other genetic diseases like cystic fibrosis, Tay-Sachs disease and sickle cell disease.
An amniocentesis procedure for genetic testing is typically performed between 15 and 20 weeks of pregnancy. Under ultrasound guidance, a needle is inserted through the abdomen to remove a small amount of amniotic fluid. The cells from the fluid are then cultured and a karyotype analysis — an analysis of the chromosomal make-up of the cells — is performed. It takes about two weeks to receive the results of the test.
Amniocentesis detects most chromosomal disorders, such as Down syndrome, with a high degree of accuracy. Testing for other genetic diseases, such as Tay-Sachs disease, is not routinely performed but can be detected through specialized testing if your fetus is known to be at risk. Testing for neural tube defects, such as spina bifida, also can be performed.
There is a small risk of miscarriage as a result of amniocentesis — about 1 in 100 or less. Miscarriage rates for procedures performed at UCSF Medical Center are less than 1 in 350.
Chorionic Villus Sampling (CVS) — Like amniocentesis, chorionic villus sampling is used most commonly to identify chromosomal problems such as Down syndrome. It can detect other genetic diseases like cystic fibrosis, Tay-Sachs disease and sickle cell disease in at-risk fetuses. The main advantage of CVS over amniocentesis is that it is done much earlier in pregnancy, at 10 to 12 weeks rather than 15 to 20 weeks.
CVS involves removing a tiny piece of tissue from the placenta.
Under ultrasound guidance, the tissue is obtained either with a needle inserted through the abdomen or a catheter inserted through the cervix. The tissue is then cultured and a karyotype analysis of the chromosomal make-up of the cells is performed. It takes about two weeks to receive the results.
The advantage of CVS over amniocentesis is that the test is performed much earlier in pregnancy, so results are typically available by the end of the third month. A disadvantage is that spinal cord defects cannot be detected. Expanded alpha fetoprotein (AFP) blood testing or ultrasound can be performed later in the pregnancy to screen for spinal cord defects.
There is a small risk of miscarriage as a result of CVS — 1 in 100 or less. Miscarriage rates for procedures performed at UCSF Medical Center are less than 1 in 350.
Ultrasound — The primary purpose of ultrasound is to determine the status of a pregnancy — the due date, size of the fetus and if the mother is carrying multiples.
Ultrasound also can provide some information about possible birth defects in a fetus. All patients at UCSF Medical Center undergo a comprehensive ultrasound examination before any invasive tests are performed. Results of the ultrasound are explained at the time of the visit.
In some patients, an ultrasound raises concern of a possible abnormality in the fetus. We have extensive experience in performing and interpreting ultrasounds in pregnancy.
If You Receive a Positive Result
If you receive positive results on a screening test, we recommend that you discuss this with your doctor and a genetic counselor. Options for further diagnostic testing will be explained. The decision as to whether to have invasive genetic testing is up to you.
If a diagnostic test finds a genetic abnormality, the significance of such results should be discussed with experts familiar with the condition, including a medical geneticist and a genetic counselor, as well as your own doctor.
Screening tests for Down syndrome in the first 24 weeks of pregnancy
Relevance
Down's syndrome (also known as Down's disease or Trisomy 21) is an incurable genetic disorder that causes significant physical and mental health problems and disability.
However, Down syndrome affects people in completely different ways. Some have significant symptoms, while others have minor health problems and are able to lead relatively normal lives. There is no way to predict how badly a child might be affected.
Expectant parents during pregnancy are given the opportunity to have a screening test for Down syndrome in their baby to help them make a decision. If a mother is carrying a child with Down syndrome, then a decision should be made whether to terminate the pregnancy or keep it. The information gives parents the opportunity to plan life with a child with Down syndrome.
The most accurate screening tests for Down syndrome include amniotic fluid (amniocentesis) or placental tissue (chorionic villus biopsy (CVS)) to identify abnormal chromosomes associated with Down syndrome. Both of these tests involve inserting a needle into the mother's abdomen, which is known to increase the risk of miscarriage. Thus, screening tests are not suitable for all pregnant women.
Therefore, more often take blood and urine tests of the mother, and also conduct an ultrasound examination of the child. These screening tests are not perfect because they can miss cases of Down syndrome and are also at high risk of being positive when the child does not have Down syndrome. Thus, if a high risk is identified using these screening tests, further amniocentesis or CVS is required to confirm the diagnosis of Down syndrome.
What we did
We analyzed combinations of serum screening tests in the first (up to 14 weeks) and second (up to 24 weeks) trimesters of pregnancy with or without ultrasound screening in the first trimester. Our goal was to identify the most accurate tests for predicting the risk of Down syndrome during pregnancy. One ultrasound index (neckfold thickness) and seven different serological indexes (PAPP-A, total hCG, free beta-hCG, unbound estriol, alpha-fetoprotein, inhibin A, ADAM 12) were studied, which can be used separately, in ratios or in combination with each other, obtained before 24 weeks of gestation, thereby obtaining 32 screening tests for the detection of Down's syndrome.
We found 22 studies involving 228615 pregnant women (including 1067 fetuses with Down syndrome).
What we found
During Down Syndrome screening, which included tests during the first and second trimesters that combined to determine overall risk, we found that a test that included neckfold measurement and PAPP- A in the first trimester, as well as the determination of total hCG, unbound estriol, alpha-fetoprotein and inhibin A in the second trimester, turned out to be the most sensitive, as it allowed to determine 9out of 10 pregnancies associated with Down syndrome. Five percent of pregnant women who were determined to be at high risk on this combination of tests would not have a child with Down syndrome. There have been relatively few studies evaluating these tests, so we cannot draw firm conclusions or recommendations about which test is best.
Other important information to consider
Ultrasounds by themselves have no adverse effects on women, and blood tests can cause discomfort, bruising, and, in rare cases, infection.
However, some women who have a high-risk Down syndrome baby on screening and who have had an amniocentesis or CVS are at risk of miscarriage of a non-Down syndrome baby. Parents will need to weigh this risk when deciding whether to perform amniocentesis or CVS after a "high risk" screening test is identified.
Translation notes:
Translation: Abuzyarova Daria Leonidovna. Editing: Prosyukova Ksenia Olegovna, Yudina Ekaterina Viktorovna. Project coordination for translation into Russian: Cochrane Russia - Cochrane Russia (branch of the Northern Cochrane Center on the basis of Kazan Federal University). For questions related to this translation, please contact us at: [email protected]; [email protected]
Diagnosis of Down syndrome by ultrasound, timing of the examination, signs of fetal chromosomal pathology
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Ultrasound
It is possible to diagnose Down's syndrome already in the early stages of pregnancy according to ultrasound examination (ultrasound) of the fetus .
The method is based on the use of high-frequency sound, which is reflected from various surfaces with different intensities. Deciphering the signals allows the doctor to create a two-dimensional image of the internal structure of the area under study.
Is it possible to detect Down syndrome by ultrasound
Down syndrome in the fetus is diagnosed by ultrasound in 60-90% of cases. High accuracy of the examination is achieved by comparing the development of the fetus with the norm. In addition to Down syndrome, ultrasound can detect signs of a number of other genetic malformations. Pathologies in the structure of the heart, incomplete rotation of the intestine, duodenal atresia can also serve as signs of Down syndrome in the fetus, all these malformations are recorded by ultrasound.
Tests before marriage
Down syndrome is observed in one case in 700-800 pregnancies and is characterized by the presence of an extra 21st chromosome. The syndrome affects the future life of the child.
The possibility of having a child with Down syndrome increases with the age of the parents. In addition, the risk of a chromosomal abnormality increases significantly if one of the parents already has Down syndrome. In some cases, the pathology is mosaic in nature and may be invisible even to very close people.
Down's syndrome is reliably diagnosed in the perinatal period using ultrasound and a number of other methods.
How does Down's syndrome appear after birth?
Children with Down syndrome have a number of external differences. Their faces are flatter, with a slightly pronounced bridge of the nose and an epicanthal fold at the inner corners of the eyes. The skull of the child is shortened, with a flat occiput.
After birth, children with Down syndrome are somewhat behind in physical and mental development. Over time, the mental retardation, in comparison with other children, will be more and more noticeable.
In addition, people with Down syndrome are more likely to suffer from congenital heart defects (they occur in almost 40% of cases).
The presence of an extra chromosome significantly increases the risk of developing some other diseases: cataracts, Alzheimer's, myeloid leukemia, and often there are disorders in the digestive system. Weakened immunity makes people with the syndrome more vulnerable to viruses and colds.
Methods for diagnosing chromosomal abnormalities
Chromosomal abnormalities can be diagnosed by non-invasive and invasive methods. The first allow you to establish a number of pathologies characteristic of chromosomal abnormalities. Invasive methods are used to make an accurate diagnosis.
ultrasound
Establishing the risk of Down syndrome in a fetus by ultrasound is called ultrasound screening. Often the method is used in combination with a biochemical analysis of the mother's blood. Accuracy of Down Syndrome Diagnosis by Ultrasound in the second trimester of pregnancy can reach 91%. The examination is carried out at 11-13 and 16-18 weeks of pregnancy.
Invasive techniques
Invasive prenatal diagnosis can lead to a number of complications. The risk to the fetus and mother is small. However, the procedure is prescribed only if necessary, if Down's syndrome in the fetus is confirmed by ultrasound data and maternal blood tests.
Biochemical screening
The main task of screening is to identify risk groups in terms of having a child with serious illnesses, including those with chromosomal disorders. Biochemical screening is recommended for all women in the first and second trimesters of pregnancy.
Diagnostics in the first trimester of pregnancy
In the first trimester of pregnancy, Down syndrome can be diagnosed by ultrasound, due to the presence of a number of pathologies. These include increased thickness of the nuchal space in the fetus, smaller than normal sizes of the cerebellum and frontal lobe, impaired bone formation, heart defects, missing nasal bone, etc.
It is important to remember that no marker will be considered sufficient for a reliable diagnosis of Down syndrome - only ultrasound data is not enough for this.
Therefore, having received the results of the examination, you do not need to be upset ahead of time - you need to consult a specialist.
What to do if the diagnosis is confirmed?
Examination can show pathology in the fetus. It is up to the parents to decide what to do next. If they are ready for responsibility, then, even if Down syndrome is confirmed by ultrasound and invasive research methods, parents can leave the child. Despite the peculiarities of development, he can live a long and happy life. In cases where there are too many pathologies, doctors may recommend terminating the pregnancy. However, even in this case, the decision will be made by the parents.
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