A pregnancy test used to detect disorders in the brain or spinal column is the:

INFORMATION

Background

Neural tube defects (NTDs) are severe birth defects of the central nervous system that originate during embryonic development when the neural tube fails to close completely. They can affect the brain, spine, or spinal cord. NTDs happen in the first month of pregnancy, often before a woman even knows that she is pregnant.

The two most common forms are spina bifida and anencephaly1:

In spina bifida, the fetal spinal column doesn’t close completely which leads to a protrusion of the spinal cord and/or meninges through the opening. This typically results in nerve damage that causes at least some paralysis of the legs.
In anencephaly, most of the brain and skull do not develop. Babies with anencephaly are usually either stillborn or die shortly after birth.

Clinical Diagnosis

Neural tube defects can result in variable paralysis and sensory loss in the legs, orthopedic deformities, scoliosis, neurogenic bowel and bladder, hydrocephalus, and Chiari II malformations. They are often associated with non-verbal learning disability and executive dysfunction, although intelligence is typically not impaired. Some cases can be very mild and not cause any significant health concerns. Most NTDs are detected antenatally on ultrasound or clinically at birth.2

Testing

NTDs are usually diagnosed during pregnancy through laboratory or imaging tests.3 Prenatal laboratory tests may include:

“Triple or Quad screen” blood test: one part of this blood test looks for an elevated level of alpha-fetoprotein (AFP), which is associated with a higher risk of NTDs. The AFP test also can be done by itself. This test generally is done during the second trimester.
Amniotic fluid tests: testing amniotic fluid may also show a high level of AFP, as well as high levels of acetylcholinesterase. Health care providers might perform this test to confirm the high levels of AFP seen in the triple/quad screen blood test. The amniotic fluid also can be tested for chromosomal abnormalities, which might also be the cause of the abnormal AFP level.

Treatment

There is no cure for neural tube defects. The nerve damage and loss of function that are present at birth are usually permanent. However, a variety of treatments e.g. fetal surgery for spina bifida4 can sometimes prevent further damage and reduce complications.

Inheritance

The exact causes of neural tube defects aren’t known. A woman is at a greater risk of having an infant with a neural tube defect if she has obesity, poorly controlled diabetes or takes certain antiseizure medicines. Getting enough folic acid, a type of B vitamin, before and during pregnancy lowers the chance for most neural tube defects.

Instruments for NTD screening

AutoDELFIA® immunoassay system

AutoDELFIA® immunoassay system for prenatal & neonatal screening with fully automated batch-loading

VICTOR2™ D fluorometer

Fluorometer designed for clinical use with all PerkinElmer diagnostic and screening assays based on either time-resolved fluorescence or prompt fluorescence.

Prenatal screening – DELFIA® Xpress platform

Random Access immunonanalyzer platform for prenatal screening

Compatible Kits

AutoDELFIA® hAFP kit

DELFIA® Xpress hAFP kit

DELFIA® hAFP kit

ARTICLES & RESOURCES

Articles and resources

ARTICLES & RESOURCES

References

https://medlineplus.gov/neuraltubedefects.html
https://bestpractice.bmj.com/topics/en-gb/1161
https://www.nichd.nih.gov/health/topics/ntds/conditioninfo/diagnosed
https://www.chop.edu/treatments/fetal-surgery-spina-bifida/about

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Neural tube defects are abnormalities that occur in the development of the spinal cord and brain of some babies. The most common defects are spina bifida (abnormal development of part of the spine and spinal cord) and anencephaly (severely abnormal development of the brain).

What are neural tube defects?

During the first month of life, an embryo (developing baby) grows a primitive tissue structure called the ‘neural tube’. As the embryo develops, the neural tube begins to change into a more complicated structure of bones, tissue and nerves that will eventually form the spine and nervous system.

However, in cases of spina bifida, something goes wrong with the development of the neural tube and the spinal column (the ridge of bone that surrounds and protects the nerves) does not fully close. Spina bifida is a Latin term that means ‘split spine’.

The chance that a pregnancy will be affected by a neural tube defect is less than one in 1,000.

What causes neural tube defects?

The cause of neural tube defects is not certain, but it appears to be due to a combination of genetic and environmental factors.

Women are at increased risk of having a baby with a neural tube defect if:

they have already had a baby with a neural tube defect
they or their partner have a close relative born with a neural tube defect
they have type 1 (insulin dependent) diabetes (not gestational diabetes)
they are obese, or take certain anti-epileptic medications, especially those containing sodium valproate or valproic acid

Prevention

About 2 in 3 neural tube defects can be prevented through increasing folate (folic acid) intake at least a month before pregnancy and during the first 3 months of pregnancy. Adequate folate levels are critical during the early days of the developing embryo, particularly the 3rd and 4th week, the period in which neural tube defects occur and when many women won't know they are pregnant.

You can increase your folate intake by eating folate-rich foods, including folate-fortified foods in your daily diet, or by taking a folic acid supplement. Good sources of folate include green leafy vegetables, fruit (citrus, berries and bananas), legumes and some cereals (bread and many breakfast cereals now have added folate).

Women who take medicines to control epilepsy, seizures or psychiatric disorders should talk to their doctor before taking folate because it can interfere with how their medications work.

For more information see folate and pregnancy.

Diagnosis

Neural tube defects may be diagnosed during the ultrasound scan that is carried out around week 12 of the pregnancy or, more likely, during the anomaly scan that is carried out at around weeks 18 to 20.

Ultrasound scans

An ultrasound scan is a safe procedure that uses sound waves to create an image of the inside of your body. Most hospitals will offer women at least 2 ultrasound scans during their pregnancy. The first is usually at around 8 to 14 weeks and is sometimes called the ‘dating scan’ because it can help to determine when the baby is due. This first scan may be able to detect problems with your baby’s spine that could indicate spina bifida if the condition is severe. If a dating scan is done earlier than 12 weeks, another ultrasound called the nuchal translucency scan is done at 12 weeks to check amongst other things for signs of Down Syndrome, and if a dating scan is not done prior to this then this scan can be used as the dating scan.

Morphology scan

The morphology or anomaly scan is an ultrasound scan that is carried out around weeks 18 to 20 of your pregnancy. This scan aims to identify any physical problems with your baby. It is usually during this scan that spina bifida is diagnosed.

Coping with the results

If tests confirm that your baby has spina bifida, the implications will be fully discussed with you. You will need to consider your options carefully. Your options are to:

continue with your pregnancy while getting information and advice so that you are prepared for caring for your baby
end your pregnancy

If you are considering ending your pregnancy, you should talk to your doctor or midwife. They will be able to provide you with important information and advice.

Your options for ending your pregnancy will depend on how many weeks pregnant you are when you make the decision. If you decide to end your pregnancy, you may wish to talk to a counsellor afterwards. Your doctor or midwife will be able to arrange this for you.

Call Pregnancy, Birth and Baby on 1800 882 436 to discuss your options regarding your pregnancy with a maternal child health nurse.

What are three types of prenatal tests?

The following screening methods are available during pregnancy: Alpha-fetoprotein (AFP) test or multiple marker test. Amniocentesis. Chorionic villus sampling.

What tests can be used to detect abnormality in the fetus?

Chorionic villus sampling and amniocentesis are used to detect abnormalities in a fetus. During both procedures, ultrasonography is used for guidance.

What is diagnostic test in pregnancy?

Diagnostic tests are offered to women whose screening tests show: they have a higher chance of being a carrier for (or having) sickle cell or thalassaemia. a higher chance their baby may have either Down's syndrome, Edwards' syndrome, or Patau's syndrome.

Which of the following is a procedure used to identify disease causing genes in an eight cell embryo?

Preimplantation genetic diagnosis (PGD) is a procedure that allows embryos to be tested for genetic disorders before they enter the uterus and before pregnancy has begun.