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Prenatal testing is an examination of the fetus performed during intrauterine development to rule out birth defects, birth defects and chromosomal aberrations such as neural tube defects, Down syndrome, Edwards syndrome, and other birth defects.
Prenatal testing
Prenatal tests are performed with the best interests of the child and its parents in mind. Thanks to advanced medicine, it is possible to identify serious defects and diseases of a child at an early stage of pregnancy. In addition, prenatal testing provides information on the inheritance of disease and the consequences of giving birth to a sick or handicapped child. Some medical conditions are treatable even before the baby is born in the womb. Also, doctors who have knowledge about the baby’s disease can better prepare for childbirth and provide specialist help.
Prenatal testing can detect diseases such as:
- hemophilia,
- cystic fibrosis,
- Duchenne muscular dystrophy,
- fenyloketonuria,
- down syndrome,
- Edwards syndrome,
- pląsawica Huntingtona,
- urinary system defects,
- Patau team,
- Turner syndrome,
- umbilical hernia,
- meningeal hernia,
- androgyness,
- anemia,
- heart defects.
In Poland, prenatal falls are especially recommended for women who have finished 35 years old, as well as women who have had a child with the defect or have genetic disorders in their family.
Types of prenatal examinations
Prenatal tests are divided into non-invasive and invasive.
- Non-invasive tests – are safe for the developing fetus in the womb and allow to assess the possible risk of diseases without endangering the baby. They are mainly based on ultrasound (so-called genetic ultrasound) and blood tests, they are completely safe for the baby, but they do not give certainty for possible fetal defects, and only allow you to estimate the approximate risk of abnormalities. In an uneventful pregnancy, it is recommended to perform three ultrasound examinations: between the 11th and 14th week of pregnancy, around the 20th week of pregnancy and around 30th. the child’s developmental stage at a certain stage of pregnancy and whether the pregnancy is single or multiple and the sex of the child. In addition, an ultrasound scan allows the doctor to diagnose spina bifida.
Other non-invasive tests include:
AFP blood test – detection of AFP (alpha-fetoprotein) in the blood allows to recognize the presence of a defect of the spinal cord and the brain (e.g. spinal hernia). A high level of alpha-fetoprotein in the mother’s blood may mean that the baby has a problem with the nervous system. In such cases, it is recommended to repeat this examination or perform an ultrasound examination.
Genetic ultrasound – it differs from ordinary ultrasound in that it is much more sensitive and performed by an experienced specialist in this field. The duration of the genetic ultrasound is approximately one hour. The ultrasound examines the thickness of the nuchal fold, yolk sac, dimensions and shape of internal organs, baby’s nasal bone, heart rate, amniotic fluid, placenta, femoral length and umbilical cord. Genetic ultrasound allows to detect, among others, Down’s, Turner and Edwards’ syndromes, but also congenital heart defects, hydrocephalus and spina bifida.
Triple level test of estriol, AFP and hCH – Its use allows the detection of Down’s syndrome, but the effectiveness of the test decreases with the age of the mother. During the test, a blood sample is taken and sent for biochemical analysis. The waiting time for the test result: from a few days to a week. Price: about PLN 250.
NIFTY study – this test has been used in Poland recently. It is similar to the above-mentioned non-invasive prenatal test, which, based on the child’s DNA analysis, determines the risk of fetal defects. For the test, material isolated from the blood of a pregnant woman is needed. The sensitivity of this test is over 99%. Price: approx. PLN 2500.
Test PAPP-A – which allows the diagnosis of Down syndrome, Edwards syndrome and Patau syndrome. Price: from 250 PLN.
Non-invasive tests are 100% safe for a child, but their conduct does not guarantee that the child does not have any genetic or congenital abnormalities. This method allows to estimate the approximate risk of their occurrence.
- Invasive tests – are based on the collection of material containing cells from the fetus. Invasive tests require puncturing of the abdominal wall in order to reach the fetal bladder, but due to the possibility of a thorough examination of the collected material, most of the known defects and congenital abnormalities of the fetus can be ruled out with certainty. There is a certain risk of miscarriage associated with the procedure itself, so invasive prenatal testing is only performed when the risk of abnormalities in the fetus is high. The decision in this matter is always made by the doctor at the genetic clinic in consultation with the patient
Invasive prenatal examinations include:
Amniocentesis – is the most frequently performed prenatal test. Aminopuncture is performed between 13-15. week of pregnancy. Given that the test itself has a high risk of miscarriage, it is only offered to women who are at high risk, such as Down’s syndrome. The examination consists in taking a material from the amniotic fluid after a previous puncture of the abdominal wall and the fetal bladder, under ultrasound guidance. The collected material includes cells from the amniotic system, digestive system, skin and the genitourinary system. Their chromosome set is determined. The test result is obtained after about a month. Price: from 1300 to 2000 PLN
Trophoblast biopsy, i.e. the structure from which the placenta will develop later in pregnancy, which consists in taking a tissue sample. The test is performed around the 10th week of pregnancy. The tissue sample is collected using a fine needle through the cervical canal or the abdominal wall. Biopsy results are obtained much faster (several days) than amine function, however, it is associated with a higher risk of miscarriage. Price: from PLN 1500
cordocentesis — a method based on collecting umbilical cord blood. This is a very difficult prenatal test and very risky at the same time. It consists in puncturing the abdominal wall under local anesthesia, and then collecting blood from the umbilical vein. On the basis of the collected material, it is possible to determine the child’s karyotype and DNA, thanks to which it is possible to know the answer to the question whether the child is burdened with a genetic disease and what disease it is. In addition, cordocentesis allows to determine the child’s blood group and diagnose, for example, congenital infection of the fetus. The test result is obtained up to 2 weeks.
Fetoscopy (speculum examination of the fetus) – is an examination involving the insertion of a special optical instrument into the uterine cavity, through the abdominal wall, which determines the level of development of a child. In addition, during fetoscopy, a child’s blood and skin sample is collected in order to diagnose possible blood diseases, especially in families with a genetic burden. Additionally, fetoscopy is a useful test for basic fetal surgery, e.g. drainage of hydrocephalus. Like other invasive tests, fetoscopy carries the risk of miscarriage or preterm labor and leakage of amniotic fluid.
Prenatal tests – indications
The main indications for prenatal testing in a pregnant woman are:
- age of the pregnant woman over 35 years of age (pregnant women after the age of 42 should not undergo the triple test because there is a high probability of obtaining a false result),
- a defect of the central nervous system in the current pregnancy,
- chromosomal mosaicism in parents,
- chromosomal translocations in parents,
- giving birth to a child with a genetic or developmental defect in a previous pregnancy,
- sex chromosome aberrations in previous pregnancies,
- genetic burden in the family (both in mother and father),
- noticing certain abnormalities during ultrasound examination,
- detection by a triple test in the serum of a pregnant woman of high concentration of AFP, which may suggest spina bifida.
Advantages of prenatal tests
1. A doctor’s selection of appropriate tests for a specific fetal defect.
2. Preparing yourself, family and relatives for the birth of a sick child.
3. Awareness of the child’s illness allows you to seek advice from other parents who are in a similar situation. Mutual support is very important.
4. Possibility of referring the pregnant woman to a specialized center with doctors with more experience in terms of pregnancy with a specific defect.
5. Lots of time to find the right hospital for delivering a sick baby. Lack of awareness that our child is sick and having him or her, e.g. in a poviat hospital without neonatology wards, may worsen the toddler’s condition due to the lack of specialist help.
6. Possibility of treating congenital defects and complications already at the stage of fetal life, in the womb.
7. Faster diagnosis. Due to the lack of prenatal tests, parents often go from specialist to specialist with their children and seek diagnostic help.
Is prenatal testing mandatory?
It is the doctor’s duty to inform the patient about the possibility of screening, and if there is a suspicion of any defects in the child – to extend the diagnosis to include prenatal tests. The decision to make them always rests with the woman. If she is at an increased risk, prenatal tests are reimbursed because the woman is referred for them.
In Poland, tests are carried out in the scope of the necessary minimum, and often a woman has no idea about all the possibilities of medicine that she can use. Most children with Down’s syndrome are born to women before the age of 35 who have not been referred for medical examinations.