Chromosomal abnormalities in the fetus: risk factors and diagnosis. Sonographic signs of chromosomal abnormalities of fetal development Low risk of chromosomal pathology of the fetus

Revealing a congenital pathology in a child will destroy the happiness of the expectant mother. Chromosomal abnormalities of the fetus can be detected during the initial examination in the 1st trimester of pregnancy: it is important not to miss the optimal timing and follow all the doctor’s instructions.

The correct set of chromosomes determines the health of the baby

Fetal chromosomal abnormalities - what is it?

The miracle of the birth of a new life begins with the fusion of two germ cells - a sperm and an egg. The genetic material of the parents from which a new person is formed must have a standard set of chromosomes. Any hereditary or acquired defect can cause chromosomal abnormalities in the fetus. This may be an insufficient number or excess of chromosomes, minor disturbances in individual structures - regardless of the reasons, genetic aberrations become the basis for the pathology of the embryo, which impairs the viability of the growing organism.

Causes of intrauterine pathology

The first weeks after conception are the most dangerous time. If chromosomal abnormalities of the fetus are not associated with genetic defects of the parents, then the causes of intrauterine congenital pathology can be:

1. Aggressive chemicals;
2. X-ray radiation;
3. Ionizing radiation;
4. Toxic and potent drugs;
5. Viral infection.

It is impossible to foresee everything and prevent some external influences on a woman’s body, so it is important to strictly follow the doctor’s recommendations at the stage of preparation for pregnancy. It is optimal for a couple planning to conceive to visit a doctor for a medical genetic consultation to identify the risk of gene defects in future parents. It is necessary to leave hazardous industries (chemical factories and laboratories, x-ray rooms), stop taking certain medications, and get preventive vaccinations. Some external factors can affect male and female reproductive cells long before conception.

Typical variants of diseases

Most often, during the initial examination in the 1st trimester, the following chromosomal abnormalities of the fetus are detected:

1. Edwards disease;
2. Patau syndrome;
3. X-trisomy;
4. Shereshevsky-Turner syndrome.

Typical external defects associated with chromosomal aberrations and detected during examination within 12-13 weeks include:

1. Defect of the fetal skull;
2. Skeletal bone abnormalities;
3. Developmental defects in the cardiovascular and genitourinary systems;
4. Craniofascial defects;
5. Mental retardation.

Non-invasive prenatal screening, including ultrasound and blood tests, will help assess the risk of congenital pathology; invasive examination techniques (amniocentesis, cordocentesis) will confirm chromosomal defects in the fetus.

The expectant mother needs to take care of the baby's health in advance

Chromosomal abnormalities of the fetus - what could be the outcome?

In most cases, nature itself makes natural selection, stopping the development of a non-viable embryo. Chromosomal abnormalities account for 50-60% (spontaneous abortions up to 8-10 weeks and at least 10% of all cases of intrauterine death of a child). However, undiagnosed birth defects are one of the reasons for the birth of a sick child (0.4% of all births). On average, per 10 million population, about 3 thousand children are born annually with various types of congenital and hereditary pathologies. The life expectancy of disabled people from childhood is no more than 35 years. No expectant mother wants to have a sick baby. You wouldn’t wish such a fate on any married couple, so it’s important to take care of the future ahead of time, following the doctor’s recommendations for preconception preparation and

They are called sunny children, they bring their parents a lot of bright joy and the greatest sorrow. Children with Down syndrome can be born into absolutely any family. Even if healthy children were born before, there is still a chance that the cells will fail during division, and the karyotype (set of chromosomes) of the newborn will be represented by 47 chromosomes instead of the required 46. In this case, the chromosomes of the last 21st pair will be absolutely identical. Hence the name of the diagnosis - trisomy 21. Currently, markers of chromosomal pathology of the fetus make it possible to identify Down syndrome. In other words, these are signs by which the doctor can predict whether the child will be born healthy or not.

Main types of markers

There are quite a few signs of Down syndrome. It should be immediately noted that there is no need to panic if suddenly the doctor writes about the presence of one of them. Even if there are several markers, the child will most likely be born healthy. So, the main physical pathologies of the fetus can be examined by ultrasound. The main symptom is an increase in the collar space. At 10-12 weeks, the width of the neck fold should not exceed 2.5-3 mm. However, if there is an excess, then it’s okay. Even if the thickness is about 9 mm, the probability of having a child with Down syndrome will still not be 100%. With slight excesses, the likelihood of pathology is minimal.

A very common sign of chromosomal pathology of the fetus, which expectant mothers are afraid of, is the reverse movement of blood in the umbilical cord. This is indeed a fairly serious violation that can lead to the destruction of the fetus. However, at short stages of pregnancy, reverse blood flow can be detected erroneously. It can pass not through the artery itself, but through the vena cava, where it may well exist without harm to the child. At the same time, if you have such suspicions, you should come for examination more often.

External markers of fetal pathology in later stages of pregnancy may be the following: the presence of a small chin, rapid heartbeat, flat bridge of the nose, “Mongolian” epicanthus. Of course, other anomalies that can be identified by experienced doctors also affect the diagnosis. The special shape of the arms, legs, face, back of the head - all this can be an additional sign of Down syndrome. During the examination, you need to pay attention to the presence of an umbilical cord cyst, swelling of the back, and the length of the nasal bones.

As for chemical indicators, doctors traditionally study the level of PAPP-A protein. Normally, in pregnant women, the protein concentration increases, so its low level may indicate the development of Down syndrome and other pathologies.

Ultrasound - the first stage of examination

Ultrasound examination is carried out both at 10-12 weeks and at later stages of pregnancy. Of course, it is mainly aimed at identifying a frozen or ectopic pregnancy. But if, for example, there is a threat of a child with Down syndrome, then the echoscopist doctor focuses on this.

If trisomy is suspected, an ultrasound scan follows a specific plan. First of all, it is determined whether there is an increase in the thickness of the collar space. Next, the nasal bones of the fetus are analyzed to see if they are reduced. Sometimes the nasal bones are completely absent, which is also a marker of chromosomal pathology. The final stage of the external examination is to identify the facial angle. If it is more than 88.5 degrees, then this is also a sign of a possible disease.

The second part of the ultrasound examination relates to the examination of the fetal cardiovascular system. The venous duct is examined for reverse blood flow, the tricuspid valve of the heart, and the presence of various anomalies is detected. The heart rate is also checked.

Ultrasound examination of pregnant women is done in two ways. The first is classic - it is performed externally, the peritoneum is checked. The second method is transvaginal. It is quite unpleasant, and the woman is required to drink about half a liter of water before the examination. The transvaginal method involves invasion through a special vaginal sensor. This method is more accurate; for example, it measures the collar space almost perfectly. However, one must understand that any ultrasound may not provide a complete picture. For example, due to the umbilical cord wrapped around the neck, measuring the collar area is absolutely unrealistic. The woman's physique may be such that the fetus can barely be seen. In addition, the doctor’s experience plays a big role. He must not only be good at taking measurements, but also know the smallest nuances of the structure of the fetus. That is why you always make an appointment with good doctors a month in advance.

The first ultrasound is usually done at 12 to 13 weeks. It allows you to identify initial markers of the threat of Down syndrome. The second ultrasound is performed at 20-22 weeks, the third - shortly before birth. Usually, an experienced doctor can tell about the presence of chromosomal abnormalities with a probability of up to 70-80%.

Biochemical screening

As a rule, doctors refer for biochemical screening somewhat earlier than ultrasound. This is done precisely because if screening shows the likelihood of Down syndrome and other abnormalities, then this can be more thoroughly checked with ultrasound. It is worth noting that in some cities of Russia such an analysis is mandatory for all pregnant women. But in some places they take it voluntarily. Therefore, it is better to do it before the ultrasound.

Biochemical screening involves taking a woman’s venous blood for analysis. There is one small but very important condition: this procedure should only be done from 11 to 13 weeks of pregnancy. After week 14, the significance of the PAPP-A protein for research is significantly lost, and therefore the diagnosis will be very inaccurate.

So how does it all work? The PAPP-A protein is part of a hormone called human chorionic gonadotropin; in all documents and certificates it is also designated by the abbreviation hCG. This hormone is the most important indicator during pregnancy. By week 10, hCG concentration reaches its maximum. However, an excessively high level of this hormone may indirectly indicate the presence of a chromosomal pathology. And if the level of PAPP-A protein is very low, then the likelihood of trisomy 21 increases many times. The lower protein level is 0.5 MoM, and the upper limit of hCG concentration is 2 MoM. Therefore, if these indicators are critically impaired, it’s time to check the fetus with an ultrasound.

Given that technology is constantly evolving, recent developments have made it possible to release strips for determining hCG and PAPA-A levels in urine. But since the results of these strips are not yet very accurate, large hospitals continue to take blood tests.

In addition to PAPP-A, biochemical screening may involve the study of other glycoproteins. For example, in the second trimester of pregnancy, a high concentration of the SP1 glycoprotein can indicate Down syndrome. If for a healthy fetus it is 1 MoM, then for a sick fetus it is 1.28 MoM. However, the increase in SP1 may be due to other factors. The accuracy of diagnosing Down syndrome using this parameter is only 20%.

Inhibin A is a glycoprotein, one of the main markers of chromosomal pathology. It is watched in the first and second trimester of pregnancy. If the concentration of inhibin A is 1.44-1.85 MoM, there is also a high probability of having a child with trisomy 21.

Carrying out calculations

Absolutely any study of markers cannot provide an accurate diagnosis. You can only calculate the probability of having a child with chromosomal abnormalities. Considering that many parameters are being studied, correct calculation of patterns and probabilities would take a lot of time from doctors. Therefore, specialized software is used for calculations. Using this software, individual risk is calculated.

How to interpret the results of marker processing?

If the computer calculates that the risk of having a child with pathologies is lower than 1:1000, you don’t have to worry too much.

In this case, there is no point in going for repeated examinations. If the risk is higher, for example, from 1:999 to 1:200, then it is better to repeat the biochemical screening in the second trimester, and again undergo an ultrasound at 15-17 weeks. Again, with average risk indicators, the chances of giving birth to a healthy child still remain maximum. If the risk is a proportion of 1:100 or higher rates, for example, 1:10, then the pregnancy will have to be paid more attention and undergo the necessary repeated examinations.

If the computer reveals a high probability of pathology, it is worth reviewing the test data yourself again. They could simply be entered incorrectly into the computer, and the examinations themselves could be carried out with errors. Considering that doctors work with a huge number of pregnant women, the human factor plays a very important role. Therefore, there is nothing special to be happy about that the system showed a low probability of the fetus having diabetes. There is always risk.

It is worth remembering that examinations prescribed in late pregnancy are less accurate than in early pregnancy. If screening was not possible within 10-14 weeks, then later tests reduce the likelihood of detecting anomalies by tens of percent.

The accuracy of the study can also be increased by studying hCG hyperglycosylate, S100 protein and some other markers. In ordinary clinics such research is rarely carried out, but in private laboratories and in some places abroad such services are provided. These markers provide about 60% accuracy in identifying diabetes.

Factors influencing the development of chromosomal pathologies

Of course, biochemical and physical markers of chromosomal pathology make it possible to predict with a high degree of probability the risk of having a child with abnormalities. However, women who are just planning to have a child often think about preliminary factors that may influence the development of such deviations. There is a very good reason for concern, because according to statistics, for every 700-800 children, 1 child is born with Down syndrome.

To a certain extent, chromosomal mutations are influenced by heredity. For example, if the husband had relatives with Down syndrome in his family, the risk increases slightly. Although it has been precisely established that there is no direct transmission of the disease from generation to generation. Moreover, if a married couple gives birth to a sick child, they may well give birth to other healthy children. The risk, of course, increases, but is not absolute. Another interesting pattern is also observed. For example, if one of the identical twins is sick with diabetes, then the second one is also sick. But if the twins are dizygotic, then, as a rule, only one child is susceptible to the chromosomal mutation.

Scientists have also found that the risk increases if there is some serious disease in the family that is inherited. There is a pattern according to which diabetes mellitus, inherited, increases the risk of having a child with diabetes.

The age of the mother also greatly influences the possible birth of a child with chromosomal abnormalities. Therefore, doctors recommend having children as early as possible. After 42 years of age, the risk increases many times over. However, newborns with Down syndrome are also found in 20-year-old women in labor. The age of the father may also increase the likelihood of anomalies to a certain extent. Usually, if the total age of the couple exceeds 70 years, then during pregnancy it is worth undergoing a full examination for the presence of markers.

Radiation radiation, serious illness during pregnancy, and experiences can affect the birth of children with diabetes.

Of course, geneticists cannot determine the exact factors influencing the birth of children with disabilities. And it is unlikely that a woman who sincerely loves a man will refuse to conceive with him because of some genetic disease. But it is quite possible to try to have a child at an earlier age, before the age of 35.

What to do if markers are detected and there is a high probability of being born with diabetes?

Every woman has her own concepts of morality and conscience. Statistics show that when performing ultrasound and biochemical screening, the probability of having a child with Down syndrome can be reduced from 1:800 to 1:1300. This can be achieved through termination of pregnancy. However, even if several markers indicate pathology, there is still a possibility that the fetus is healthy. Therefore, by terminating a pregnancy, it is quite possible to kill a healthy fetus. If a woman is older, after an abortion she may never be able to give birth.

In many countries, identifying markers is aimed at enabling the mother to psychologically prepare for the birth of a “sunny” child. Of course, it is much harder with such children than with ordinary ones. However, most families who find themselves in such a situation, although they face difficulties, still call themselves happy and love their child very much, despite the fact that he is not like everyone else. If you work with your child, he may well integrate into ordinary society. Children with Down syndrome make excellent musicians and artists, many of them are truly talented. There are cases when people with such a disease lived until they were 50-60 years old, worked, had families, and even achieved some success. It all depends on the parents, care, and how the child is treated.

There is nothing catastrophic in the birth of a child with such a pathology. But even if all the markers indicate that a child may be born with the disease, there is still a significant chance that the forecasts are misleading. Children are in any case joy and happiness, no matter how they were born.

During pregnancy, various tests and studies can diagnose chromosomal pathologies of the fetus, which are essentially hereditary diseases. They are caused by changes in the structure or number of chromosomes, which explains their name.

The main cause of occurrence is mutations in the germ cells of the mother or father. Of these, only 3-5% are inherited. Due to such deviations, about 50% of abortions and 7% of stillbirths occur. Since these are serious gene defects, parents should be more attentive to all tests prescribed throughout pregnancy, especially if they are at risk.

If parents (both) have hereditary diseases in their family, they first need to know what it is - chromosomal pathologies of the fetus, which can be detected in their child while he is still in the womb. Awareness will allow you to avoid unwanted conception, and if this has already happened, eliminate the most severe consequences, ranging from intrauterine death of the baby to external mutations and deformities after birth.

In a normal, healthy person, chromosomes are arranged in 23 pairs, and each is responsible for a specific gene. The total is 46. If their number or structure is different, they speak of chromosomal pathologies, of which there are many varieties in genetics. And each of them entails dangerous consequences for the life and health of the baby. The main causes of this type of anomaly are unknown, but there are certain risk groups.

With the world on a thread. One of the rarest chromosomal pathologies is called cry-the-cat syndrome. The reason is a mutation on chromosome 5. The disease manifests itself in the form of mental retardation and the characteristic crying of a child, which is very reminiscent of a cat's cry.

Causes

In order to prevent or promptly recognize chromosomal pathologies of the fetus during pregnancy, doctors must interview future parents about hereditary diseases and the living conditions of their family. According to recent studies, gene mutations depend on this.

There is a certain risk group, which includes:

• the age of the parents (both) is over 35 years;
• the presence of CA (chromosomal abnormalities) in blood relatives;
• harmful working conditions;
• long-term residence in an environmentally unfavorable area.

In all these cases, there is a fairly high risk of chromosomal pathology of the fetus, especially in the presence of hereditary diseases at the gene level. If these data are identified in a timely manner, doctors are unlikely to advise the couple to give birth at all. If conception has already occurred, the degree of damage to the child, his chances of survival and a further full life will be determined.

Mechanism of occurrence. Chromosomal pathologies develop in the fetus when a zygote is formed and the fusion of sperm and egg occurs. This process cannot be controlled because it has not yet been studied enough.

Signs

Since the process of occurrence and development of this type of abnormality has not been sufficiently studied, markers of chromosomal pathology of the fetus are considered conditional. These include:

• , nagging pain in the lower abdomen in the early stages of pregnancy;
• low level of PAPP-A (protein A from plasma) and AFP (protein produced by the body of the embryo), increased hCG (chorionic gonadotropin - placental hormone): to obtain such data, blood is taken from a vein to detect chromosomal pathology of the fetus at 12 weeks (+/ - 1-2 weeks);
• length of nasal bones;
• enlarged neck fold;
• fetal inactivity;
• enlarged renal pelvis;
• slow growth of tubular bones;
• early aging or hypoplasia of the placenta;
• poor results of Doppler (ultrasound method for identifying circulatory pathologies) and CTG (cardiotocography);
• - And ;
• hyperechoic intestine;
• small size of the maxillary bone;
• enlarged bladder;
• cysts in the brain;
• swelling in the back and neck;
• hydronephrosis;
• facial deformities;
• umbilical cord cysts.

The ambiguity of these signs is that each of them separately, like the entire complex listed above, can be the norm, determined by the individual characteristics of the mother or child. The most accurate and reliable data is usually provided by a blood test for chromosomal pathologies, ultrasound and invasive techniques.

Through the pages of history. Having examined the chromosomes of modern people, scientists found that they all received their DNA from one woman who lived somewhere in Africa 200,000 years ago.

Diagnostic methods

The most informative method for diagnosing chromosomal pathologies of the fetus is the first screening (it is also called a double test). Done at 12 weeks of pregnancy. It includes:

• Ultrasound (the markers indicated above are identified);
• blood test (taken from a vein on an empty stomach) showing the level of AFP, hCG, APP-A.

It should be understood that this analysis for chromosomal pathologies of the fetus cannot provide an accurate, 100% confirmation or refutation of the presence of anomalies. The doctor’s task at this stage is to calculate the risks, which depend on the research results, age and medical history of the young mother. The second screening (triple test) is even less informative. The most accurate diagnosis is invasive methods:

• chorionic villus biopsy;
• umbilical cord blood collection;
• amniotic fluid analysis.

The purpose of all these studies is to determine the karyotype (the set of characteristics of a set of chromosomes) and, in connection with this, chromosomal pathology. In this case, the accuracy of diagnosis is up to 98%, while the risk of miscarriage is no more than 2%. How is the data obtained during these diagnostic techniques deciphered?

Ultrasound and risks to the fetus. Contrary to the widespread myth about the dangers of ultrasound for the fetus, modern equipment makes it possible to reduce the negative impact of ultrasound waves on the baby to zero. So don't be afraid of this diagnosis.

Decoding and calculating risks

After the first double screening is done, ultrasound markers of fetal chromosomal pathology that were identified during the study are analyzed. Based on them, it calculates the risk of developing genetic abnormalities. The very first sign is an abnormal size of the collar space in an unborn child.

Ultrasonic markers

Absolutely all ultrasound markers of chromosomal pathology of the fetus in the 1st trimester are taken into account in order to make the necessary calculations of possible risks. After this, the clinical picture is complemented by a blood test.

Blood markers

All other indicators are considered deviations from the norm.

In the second trimester, inhibin A, unconjugated estriol and placental lactogen are also assessed. All interpretation of the research results is carried out by a special computer program. Parents can see the following values ​​as a result:

• 1 in 100 means that the risk of genetic defects in the baby is very high;
• 1 in 1000 is the threshold risk of chromosomal pathology of the fetus, which is considered normal, but a slightly underestimated value may mean the presence of some anomalies;
• 1 in 100,000 is a low risk of chromosomal pathology of the fetus, so there is no need to fear for the baby’s health from a genetic point of view.

After doctors calculate the risk of chromosomal pathology in the fetus, either additional tests are prescribed (if the obtained value is lower than 1 in 400), or the woman calmly nurses the pregnancy to a successful outcome.

This is interesting! The male Y chromosome is the smallest of all. But it is precisely this that is passed on from father to son, preserving the continuity of generations.

Forecasts

Parents whose child was diagnosed with chromosomal abnormalities in utero should understand and accept as a given that they cannot be treated. All that medicine can offer them in this case is an artificial termination of pregnancy. Before making such a responsible decision, you need to consult your doctors on the following issues:

• What exactly pathology was diagnosed?
• What consequences will it have for the life and health of the child?
• Is there a high risk of miscarriage and stillbirth?
• How old do children with this diagnosis live?
• Are you ready to become parents of a disabled child?

In order to make the right decision about whether to keep a sick baby or not, you need to objectively evaluate all the possible consequences and results of chromosomal pathology of the fetus together with a doctor. They largely depend on what kind of genetic abnormality doctors suspect. After all, there are quite a lot of them.

Interesting fact. Patients with Down syndrome are commonly called sunny people. They are rarely aggressive, most often very friendly, sociable, smiling and even talented in some ways.

Diseases

The consequences of chromosomal pathologies detected in the fetus can be very different: from external deformities to damage to the central nervous system. They largely depend on what kind of anomaly has occurred with the chromosomes: their number has changed or mutations have affected their structure. Among the most common diseases are the following.

Chromosome number disorder

• Down syndrome is a pathology of the 21st pair of chromosomes, in which there are three chromosomes instead of two; accordingly, such people have 47 of them instead of the normal 46; typical signs: dementia, delayed physical development, flat face, short limbs, open mouth, squint, bulging eyes;
• Patau syndrome - disturbances in the 13th chromosome, a very severe pathology, as a result of which numerous developmental defects are diagnosed in newborns, including idiocy, polyfingeredness, deafness, mutations of the genital organs; such children rarely live to be one year old;
• Edwards syndrome - problems with the 18th chromosome, often associated with the mother's advanced age; babies are born with a small lower jaw and mouth, narrow and short eye slits, and deformed ears; 60% of sick babies die before 3 months, and 10% survive up to a year; the main causes of death are respiratory arrest and heart defects.

Violation of the number of sex chromosomes

• Shereshevsky-Turner syndrome - abnormal formation of the gonads (most often in girls), caused by the absence or defects of the sex X chromosome; symptoms include sexual infantilism, folds of skin on the neck, deformation of the elbow joints; children with such a chromosomal pathology survive, although childbirth is very difficult, and in the future, with proper supportive treatment, women are even able to carry their own baby (through IVF);
• polysomy on the X- or Y-chromosome - a variety of chromosome disorders, characterized by a decrease in intelligence, an increased likelihood of developing schizophrenia and psychosis;
• Klinefelter syndrome is a disorder of the X chromosome in boys, who in most cases survive after childbirth, but have a specific appearance: lack of body hair, infertility, sexual infantilism, mental retardation (not always).

Polyploidy

• Such chromosomal pathology in the fetus always ends in death even before birth.

Scientists are still trying to figure out why gene mutations occur at the chromosome level. However, this is still only a matter of the future, and at this point in time, chromosomal pathologies detected in utero in the fetus account for up to 5% of all cases.

What should parents do when they hear such a diagnosis? Do not panic, reconcile yourself, listen to the doctors and, together with them, make the right decision - leave the sick baby or agree to an artificial termination of pregnancy.

I really want to find those who experienced this and hear how it all ended for them - this is the only thing that will help me not go crazy now.

I am 26, I have a daughter who is almost 4 years old. Second pregnancy - 17 weeks. From 12 weeks my life became hell as soon as I had my first ultrasound. It took place in our perinatal center.
It showed an increase in the collar space - 2.3 mm, dilated pelvis, heart rate - 173 beats/min and bladder - 6 mm. I donated blood and according to their program everything turned out fine. They raised the risk of a megacystic due to the bladder and offered a referral for an abortion while it was still possible in terms of timing. I refused and was scheduled for a repeat ultrasound in a week.

I couldn’t stand it and went to a paid clinic the day before the next ultrasound - they removed the suspicion of a megacystic, because the urinary tract was 2 mm - the baby peed, but the collar space increased - 2.8 mm. We found a hyperechoic focus in the heart.
The next day, the perinatal ultrasound revealed exactly the same thing. A repeat ultrasound was scheduled in 3 weeks.

Yesterday I had an ultrasound. Heartbeat - 167 beats/min, hyperechoic focus in the heart, slightly dilated pelvis, but above normal, and choroid plexus cysts up to 3.9 mm. A local geneticist insists that all these are minor markers of chromosomal abnormalities of the fetus. It was proposed to do an invasive diagnosis of amniotic fluid for 5 types of abnormalities, but it was also stipulated that most likely this analysis will not show positive results, since there are no severe anomalies according to the signs, but the points indicate that there are still violations and they may appear when the child grows up and cannot, for example, crawl or walk, he may have problems that are later discovered by a neurologist or pediatrician. And that this can no longer be cured. Sends me to Moscow to see a geneticist for more advanced diagnostics. And this means time, risks and a lot of money. And with your head you understand that you will have one of 3 results in your hands: 1) the child is healthy and this is good; 2) the child has a serious pathology and the pregnancy must be terminated so as not to live in hospitals, leaving the eldest daughter without a mother; 3) there is a certain set of deviations (to be honest, I don’t even know which ones) with which we will sit and, as now, not know what to do. They gave me 2 weeks to think and act - then everything will become useless.

Do you know what’s drilling into my head the most: I have a daughter with similar abnormalities, as they have just found in the baby - she was born with dilated pelvis and she has a slight arrhythmia. She is an absolutely healthy child and we are simply observing her characteristics with specialists in order to track her dynamics (positive, by the way). But the trouble is that 4 years ago there was no such technology and all these screenings, and by all indicators my daughter was healthy (normal). Therefore, all these coincidences are just speculation.

And I don't even know what to do...

Each pregnant woman decides for herself the complex ethical question of whether it is worth conducting an examination to identify genetic pathologies of the unborn baby. In any case, it is important to have all the information about modern diagnostic capabilities.

Yulia SHATOKHA, Candidate of Medical Sciences, Head of the Department of Prenatal Ultrasound Diagnostics at the Ultrasound Studio Network of Medical Centers, spoke about what invasive and non-invasive methods of prenatal diagnosis exist today, how informative and safe they are, and in what cases they are used.

Why is prenatal diagnosis needed?

Various methods help predict possible genetic pathologies during pregnancy. First of all, this is an ultrasound examination (screening), with which the doctor can notice abnormalities in the development of the fetus.

The second stage of prenatal screening during pregnancy is biochemical screening (blood test). These tests, also known as “double” and “triple” tests, are taken by every pregnant woman today. It allows you to predict with some degree of accuracy the risk of fetal chromosomal abnormalities.

” It is impossible to make an accurate diagnosis based on such an analysis; this requires chromosomal studies - more complex and expensive.

Chromosomal studies are not mandatory for all pregnant women, but there are certain indications:

future parents are close relatives;

expectant mother over 35 years old;

the presence in the family of children with chromosomal pathology;

miscarriages or missed pregnancies in the past;

diseases potentially dangerous to the fetus suffered during pregnancy;

shortly before conception, one of the parents was exposed to ionizing radiation (X-rays, radiation therapy);

risks identified by ultrasound.

Expert opinion

The statistical probability of having a child with a chromosomal disorder is from 0.4 to 0.7%. But it must be borne in mind that this is a risk in the population as a whole; for individual pregnant women it can be extremely high: the basic risk depends on age, nationality and various social parameters. For example, the risk of chromosomal abnormalities in a healthy pregnant woman increases with age. In addition, there is, and then there is an individual risk, which is determined on the basis of biochemical and ultrasound data.

"Double" and "triple" tests

Biochemical screenings also known as , and in common parlance referred to as "test for Down syndrome" or "test for deformities", carried out at strictly defined periods of pregnancy.

Double test

A double test is done at 10-13 weeks of pregnancy. During this blood test, they look at the following indicators:

free hCG (human chorionic gonadotropin),

PAPPA (plasma protein A, inhibitor A).

The analysis should be done only after an ultrasound scan, the data of which is also used when calculating risks.

The specialist will need the following data from the ultrasound report: date of the ultrasound, coccygeal-parietal size (CPR), biparietal size (BPR), nuchal translucency thickness (TN).

Triple test

The second, a “triple” (or “quadruple”) test, is recommended for pregnant women to take at 16-18 weeks.

This test examines the following indicators:

alpha fetoprotein (AFP);

free estriol;

inhibin A (in case of quadruple test)

Based on the analysis of data from the first and second biochemical screening and ultrasound, doctors calculate the likelihood of such chromosomal abnormalities as:

Down syndrome;

Edwards syndrome;

neural tube defects;

Patau syndrome;

Turner syndrome;

Cornelia de Lange syndrome;

Smith Lemli Opitz syndrome;

triploidy.

Expert opinion

A double or triple test is a biochemical test that determines the concentration in the mother’s blood of certain substances that characterize the condition of the fetus.

How are the risks of chromosomal abnormalities calculated?

The results of biochemical screening, in addition to possible chromosomal pathologies, are influenced by many factors, especially age and weight. To determine statistically reliable results, a database was created in which women were divided into groups by age and body weight and the average values ​​of the “double” and “triple” tests were calculated.

The average result for each hormone (MoM) became the basis for determining the normal limit. So, if the result obtained when divided by MoM is 0.5-2.5 units, then the hormone level is considered normal. If less than 0.5 MoM - low, above 2.5 - high.

What level of risk of chromosomal abnormalities is considered high?

In the final conclusion, the risk for each pathology is indicated as a fraction.

A risk of 1:380 and above is considered high.

Average - 1:1000 and below - this is a normal indicator.

A risk of 1:10,000 or less is considered very low.

This figure means that out of 10 thousand pregnant women with such a level, for example, hCG, only one had a child with Down syndrome.

Expert opinion

A risk of 1:100 or higher is an indication for diagnosing chromosomal pathology of the fetus, but each woman determines the degree of criticality of these results for herself. To some, a probability of 1:1000 may seem critical.

Accuracy of biochemical screening in pregnant women

Many pregnant women are wary and skeptical about biochemical screening. And this is not surprising - this test does not provide any accurate information; on its basis, one can only assume the likelihood of the existence of chromosomal abnormalities.

In addition, the information content of biochemical screening may be reduced if:

pregnancy occurred as a result of IVF;

the expectant mother has diabetes mellitus;

multiple pregnancy;

the expectant mother is overweight or underweight

Expert opinion

As an isolated study, double and triple tests have little prognostic value; when taking into account ultrasound data, the reliability increases to 60-70%, and only when conducting genetic tests the result will be 99% accurate. We are talking only about chromosomal abnormalities. If we are talking about a congenital pathology not associated with chromosome defects (for example, “cleft lip” or congenital heart and brain defects), then professional ultrasound diagnostics will give a reliable result.

Genetic tests for suspected chromosomal abnormalities

Based on the ultrasound conclusion or if the results of biochemical screening are unfavorable, the geneticist may suggest that the expectant mother undergo . Depending on the period, this may be a chorionic villus or placenta biopsy, amniocentesis or cordocentesis. Such a study gives highly accurate results, but in 0.5% of cases such an intervention can cause a miscarriage.

Material collection for genetic research is carried out under local anesthesia and ultrasound control. The doctor uses a thin needle to puncture the uterus and carefully remove genetic material. Depending on the stage of pregnancy, this may be particles of chorionic villi or placenta (chorionic or placental biopsy), amniotic fluid (amniocentesis) or blood from the umbilical vein (cordocentesis).

The resulting genetic material is sent for analysis, which will determine or exclude the presence of many chromosomal abnormalities: Down syndrome, Patau syndrome, Edwards syndrome, Turner syndrome (accuracy - 99%) and Klinefelter syndrome (accuracy - 98%).

” Four years ago, an alternative to this method of genetic research appeared - a non-invasive prenatal genetic test. This study does not require obtaining genetic material - it is enough to take blood from the vein of the expectant mother for analysis. The method is based on the analysis of DNA fragments of the fetus, which, during the renewal of its cells, enter the bloodstream of the pregnant woman.

This test can be done starting from the 10th week of pregnancy. It is important to understand that this test is not yet widespread in Russia, very few clinics do it, and not all doctors take its results into account. Therefore, you need to be prepared for the fact that the doctor may strongly recommend an invasive examination in case of high risks based on ultrasound or biochemical screening. Be that as it may, the decision always remains with the future parents.

In our city, non-invasive prenatal genetic tests are performed at the following clinics:

"Avicenna". Panorama test. Non-invasive prenatal genetic diagnosis of aneuploidy 42 t.r. Non-invasive prenatal genetic diagnosis of aneuploidies and microdeletions - 52 rub.

"Almita". Panorama test. Cost from 40 to 54 tr. depending on the completeness of the study.

"Ultrasound studio" Prenetix test. Cost 38 tr.

Expert opinion

Only chromosomal analysis can confirm or exclude chromosomal pathology. Ultrasound and biochemical screening can only calculate the magnitude of the risk. Analysis for pathologies such as Down syndrome, Edwards syndrome and Patau syndrome can be carried out from 10 weeks of pregnancy. This is done by obtaining fetal DNA directly from the structures of the fertilized sac (directly invasive method). The risk arising from invasive intervention, in the presence of direct indications, is guaranteed to be lower than the risk of chromosomal pathology (approximately 0.2-0.5% according to various authors).

In addition, today any pregnant woman of her own free will can undergo examination for the presence of major genetic diseases in the fetus using a direct non-invasive method. To do this, you just need to donate blood from a vein. The method is absolutely safe for the fetus, but is quite expensive, which limits its widespread use.

Difficult decision

Each woman decides for herself the question of whether diagnosis of genetic diseases is necessary during pregnancy and what to do with the information obtained as a result of research. It is important to understand that doctors do not have the right to put pressure on a pregnant woman in this matter.

Expert opinion

When the pregnancy is up to 12 weeks, a woman can decide for herself whether to terminate the pregnancy if any pathology of the fetus is detected. At a later date, compelling reasons are needed for this: pathological conditions incompatible with the life of the fetus and diseases that will subsequently lead to profound disability or death of the newborn. In each specific case, this issue is resolved taking into account the duration of pregnancy and the prognosis for the life and health of the fetus and the pregnant woman herself.

There are two reasons why doctors may recommend terminating a pregnancy:

developmental defects in the fetus that are incompatible with life or with the prognosis of profound disability of the child have been identified;

a condition of the mother in which prolongation of pregnancy can cause an unfavorable course of the disease with a threat to the life of the mother.

Prenatal diagnosis - be it biochemical, ultrasound or genetic testing - is not mandatory. Some parents want to have the most complete information, while others prefer to limit themselves to a minimum set of examinations, trusting nature. And every choice is worthy of respect.