First trimester blood test 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
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

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

Associated Procedures

Products & Services

Pregnancy tests - maternal serum screening

The maternal serum screening (MSS) test is a blood test available to pregnant women in Victoria. It helps determine the chance of their unborn child having Down syndrome (trisomy 21), Edward syndrome (trisomy 18) or a neural tube defect.

Maternal serum screening may be done in the first trimester of pregnancy, when it is combined with an ultrasound. This is called the combined first trimester screening test. Or, testing may be performed in the second trimester of pregnancy. This is called the second trimester maternal serum screening test.

Maternal serum screening tests for various conditions

MSS can identify pregnancies that are at increased chance of:

Down syndrome – a condition that results in intellectual disability of varying degrees. It may cause some physical problems such as heart defects or difficulties with sight or hearing. Down syndrome is also known as trisomy 21 because the baby has three copies of chromosome 21, instead of the usual two
Edward syndrome – a condition that results in physical problems such as growth deficiency, heart defects, digestive system defects and intellectual disability. Babies born with Edward syndrome have a poor prognosis. Many do not live beyond the first few weeks of life. Edward syndrome is also known as trisomy 18 because the baby has three copies of chromosome 18, instead of the usual two
Neural tube defects – the most common neural tube defects are anencephaly and spina bifida. With anencephaly, the brain does not develop properly and the baby does not survive. Babies with spina bifida have an opening in the bones of the spine that can result in damage to the nerves controlling the lower part of the body. This can cause weakness and paralysis of the legs, and sometimes inability to control the bowel and bladder. Neural tube defects are only screened for in the second trimester MSS test. Neural tube defects can also be diagnosed by routine ultrasound tests during pregnancy.

This test is only for these conditions. A low-chance result does not mean the baby is free of other birth defects.

Combined first trimester screening test

The combined first trimester screening test can identify a pregnancy with increased chance of Down syndrome (trisomy 21) and Edward syndrome (trisomy 18). This test involves the pregnant woman having a blood test between 9 and 13 weeks gestation, and an ultrasound between 11 and 13 weeks gestation. The blood test measures the amount of two different proteins that occur naturally in the mother’s blood during pregnancy.

Using ultrasound, a measurement of the amount of fluid in the skin at the back of the baby’s neck is taken. This measurement is called the nuchal translucency. All babies at this stage of pregnancy have fluid at the back of their neck, but babies with Down syndrome or Edward syndrome tend to have more fluid.

During the ultrasound, the specialist performing the scan may also report the presence or absence of the nasal bone. If the nasal bone is absent, there may be an increased chance of Down syndrome.

Your GP (doctor) or medical specialist can order this test. There may be gap payments depending on the service you are attending – discuss this with your health professional.

Second trimester maternal serum screening test

The second trimester maternal serum screening test can identify a pregnancy with increased chance of Down syndrome, Edward syndrome or neural tube defects. The test involves the pregnant woman having a blood test between 14 and 20 weeks + 6 days gestation. However, it is best if the blood is collected between 15 and 17 weeks gestation.

The test measures the amount of four proteins in the mother’s blood. The results are combined with the woman’s age risk to give a final chance of Down syndrome, Edward syndrome or neural tube defects. The result is reported as an increased chance or low-chance result.

Availability of the maternal serum screening test

Screening for Down syndrome and other chromosome conditions should be offered to all pregnant women. However, the decision to have testing is a personal decision. All women have the chance of having a baby with Down syndrome or Edward syndrome, although the chance increases with the age of the woman.

A low-chance maternal serum screening result does not mean there is no chance of a genetic condition being present in the unborn baby. It means that the chance is low.
Similarly, an increased chance result does not necessarily mean that the baby has a genetic condition. Most women with an increased chance result will not have a baby with Down syndrome, Edward syndrome or a neural tube defect.

Maternal serum screening test results

Maternal serum screening tests do not diagnose health conditions, but they identify women who should be offered further testing to detect if their baby has a genetic condition.

Women with an increased chance result on maternal serum screening should be offered a diagnostic test. However, it is their choice whether to have further testing.
Chorionic villus sampling (CVS) and amniocentesis are diagnostic tests that detect chromosome conditions such as Down syndrome and Edward syndrome in the unborn baby.

Genetic counselling after a maternal serum screening test

In most cases an ‘increased chance’ maternal serum screening result does not mean the baby has the condition, just that they are at an increased risk of having the condition. This is why further diagnostic testing is encouraged to provide more information about the likely health outcomes of the baby.

If your child has been diagnosed with a genetic condition it can be helpful to speak to a genetic counsellor.

Genetic counsellors are health professionals qualified in both counselling and genetics. As well as providing emotional support, they can help you to understand a condition and what causes it, how it is inherited, and what a diagnosis means for your child’s health and development. Genetic counsellors are trained provide information and support that is sensitive to your family circumstances, culture and beliefs.

The Genetic Support Network of Victoria (GSNV)External Link is connected with a wide range of support groups throughout Victoria and Australia and can connect you with other individuals and families affected by the same genetic condition.

Non-invasive prenatal testing (NIPT)

Non-invasive prenatal testing (NIPT) is an alternative to maternal serum screening. NIPT is a maternal blood test that looks at the baby’s genetic material (DNA), which can be found in the mother’s bloodstream. It can provide information about the risk of conditions such as Down syndrome and some other chromosome problems, and can be done any time from 10 weeks into the pregnancy. It is more accurate than combined first-trimester screening or second-trimester maternal serum screening, but it is more costly than the screening tests.

Where to get help

Your GP (doctor)
Your obstetrician
Victorian Clinical Genetics Services (VCGS)External Link, Royal Children’s Hospital Tel. 1300 118 247

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]

Reliability of 1st trimester screening - an article from the Lek-Diagnostic clinic network

1st trimester screening: what is it?

Screening of the 1st trimester is a comprehensive examination aimed at assessing the rate of intrauterine development of the baby by comparing the indicators of a specific gestational age. At this stage, the probability of congenital pathological abnormalities, including Down syndrome, is determined. Screening of the 1st trimester includes two procedures: a biochemical blood test and an ultrasound examination.

Biochemical blood test

Using biochemistry, you can determine the level of hormones that affect the development of genetic abnormalities:

1. B-hCG - is produced from the beginning of pregnancy, from the 9th week the indicator begins to decline. The norm is 50 thousand-55 thousand. mIU/ml.

2. PAPP-A is an A-plasma protein. A natural indicator is 0.79-6.00 mU / l. during the 1st trimester screening period.

The procedure is carried out in the period from 11 to 13 weeks. A woman donates venous blood in the morning on an empty stomach. Among the contraindications: signs of multiple pregnancy, weight problems, diabetes. Biochemistry is mandatory for women after 35 years of age, with genetic anomalies in the family, with miscarriages or infectious diseases in the past.

Ultrasound

Ultrasound is a safe and informative diagnostic method. It allows you to localize the location of the fetus, its physique, compliance with the size of the norm, and also to identify how correctly the limbs of the unborn child are located.

According to the results of the first ultrasound, the doctor:

Determines the date of conception, and also corrects the gestational age;

Establishes or refutes the fact of the presence of congenital pathologies;

Estimates the likelihood of pathological pregnancy.

Ultrasound is performed in two ways: transvaginally (the sensor is inserted into the vagina) or abdominally (the sensor is driven along the abdomen). It is optimal to perform the procedure at the 12th week of pregnancy.

Why are parents afraid of Down syndrome?

Down syndrome is a common genetic syndrome. Normally, a set of chromosomes in humans contains 23 pairs. With a genetic anomaly, a mutation of chromosome 21 leads to trisomy - the presence of an extra 21 chromosome. The pathology was first diagnosed in 1866 by John Down. At the moment, the probability of developing the syndrome is 1 in 700 children.

Why can't Down syndrome be seen on ultrasound?

It is impossible to make an accurate diagnosis of Down syndrome using ultrasound. Based on the results of the procedure, the specialist evaluates the condition of the fetus according to the following parameters:

1. Thickened neck fold. Normally, it is 1.6-1.7 mm. A thickness of 3 mm indicates the likelihood of chromosomal abnormalities.

2. KTR (fetal length). The normal figure varies from 43 to 65 mm (for a period of 12-13 weeks).

At the next stage, calculations are carried out, the risk of genetic abnormalities is examined. A probability higher than 1:360 is high - however, this is not a diagnosis, but an assumption.

What to do if you are at high risk for Down syndrome?

According to statistics, 70% of women carrying a child with Down syndrome are at risk. In this case, the woman is invited to undergo an additional examination at the medical genetic center. The specialist prescribes a series of tests and amniocentesis is practiced as an invasive diagnosis.

Features of invasive diagnostics

Amniocentesis is the analysis of amniotic fluid. The procedure is performed by puncturing the abdomen in the area of the embryonic membrane. Its result is a sample of amniotic fluid, which contains fetal cells.

Amniocentesis is performed by one of two methods: