The second screening during pregnancy: the timing, what they look at and the norms. Second screening during pregnancy: what will the second test tell about? How is 2nd trimester screening done?

The second trimester of pregnancy is carefully studied, compared with the normative data, and only then specific conclusions are drawn.

Why spend

Expectant mothers shouldn't be intimidated by the word "screening". This is a type of complex diagnosis that includes an ultrasound scan and the measurement of several hormone markers in the body of a pregnant woman. Based on the data obtained as a result of the study, conclusions are drawn about the condition of the baby. If all is well, then the parents can calmly wait for the appearance. If the conclusions are negative, certain measures are taken.

In a word, the second screening during pregnancy is a rather responsible event, the timing of which must be strictly adhered to.

Research is carried out for the following purposes:

Identification of deficiencies that could not be identified during the initial screening.
Confirm or challenge first trimester diagnoses.
Diagnose the possibility of developing pathologies.
Identification of physiological problems in the development of the baby's body.

Initial screening is believed to provide accurate predictions, but should not be relied upon. Only the norms of the second, repeated screening during pregnancy, will reveal the dynamics of the baby's development and draw accurate conclusions.

Did you know? Down and Edwards pathology is detected on screening studies only in 70% of cases. Cases are described when an absolutely healthy baby was born with suspicion of this syndrome.

Procedure safety

Despite the fact that screenings include only proven methods, their validity and harmlessness causes a lot of debate.

To establish an accurate diagnosis, one transcript taken during the 2nd screening in the second trimester of pregnancy is not enough, therefore an ultrasound scan is prescribed.
Many believe that ultrasound can harm the embryo as it negatively affects the baby's nervous system. And this is explained by the fact that during the procedure the fetus tries to hide from the apparatus and covers the head with handles.

Therefore, it is believed that babies whose mothers often had ultrasounds are more restless.

Did you know? Ultrasound helps to decipher the presence of many pathologies. With Edwards' symptoms, the fetus does not differ in the bones of the nose and the heart rate is low. And with signs of Down, the nasal bone becomes noticeable only at 15-20 weeks.

In reality, ultrasound can not harm the fetus - the latest equipment is safe. Therefore, doctors strongly advise that at the time when they do the second, re-screening during pregnancy, an ultrasound scan and a blood test must be carried out.

After all, timely diagnosis allows you to correct any problems in time.

Does everyone have to pass

For the second screening during pregnancy, not everyone is sent in a row, but only those women who are at risk, and the timing is prescribed by the doctor.

Screening can also be prescribed if:

Primary ultrasound revealed the developmental pathology.
At 14-20 weeks, the pregnant woman was ill with an infectious disease (acute form).
After 14 weeks, a neoplasm was found in the expectant mother.

Did you know? A woman can still get pregnant during pregnancy. Such cases are rare, a child conceived later is born prematurely. The difference between such babies can be four weeks.

In some cases, after 2 screening during pregnancy (no matter how many weeks it is carried out), a woman can be referred to a geneticist, who will decide whether a full-fledged perinatal examination should be done.
If the pregnancy is normal, no second screening is scheduled. But a woman can go through it at will, in order to get rid of negative emotions about and development.

After all, any mother will be able to calm down when she sees that the tests shown by the second screening during pregnancy are normal.

Indications for

This survey can be prescribed in the same directions as in the initial survey:

The baby's parents are blood relatives.
The age of the parents is 35 and over.
The pregnant woman had an acute bacterial or infectious disease.
The expectant mother has one or more pathologies that are hereditarily transmitted: sugar, oncopathology, abnormalities in the work of the musculoskeletal system.
In the genus of at least one of the parents there is a gene disease (in this case, special attention is paid to the decoding of 2 pregnancy screenings and ultrasound).
Drug addiction, alcoholism of one of the parents.
The pregnant woman has previously had miscarriages, early delivery, or already has a baby with developmental abnormalities.
Forced intake of drugs that are prohibited during pregnancy.
During the survey, it was found that fetal death occurred earlier.
Difficult working conditions of the mother.

Dates of the

If there are indications for 2 screening during pregnancy, you need to know how many weeks this medical examination is carried out.

Typically, the doctor will prescribe this procedure at 16-20 weeks.

Many doctors believe that the screening examination is best done at 22-24 weeks of pregnancy, but most experts still believe that the most informative studies are at 16-17 weeks.

How to prepare

In preparation for a re-screening examination, there are fewer requirements than before the initial one.
Taking into account the fact that the second screening during pregnancy takes place already during the period of fetal maturation, and that they look through the amniotic fluid and there is absolutely no need to replenish the bladder with fluid.

Important! Before biochemical analysis, it is not recommended to have breakfast - blood is taken on an empty stomach.

And the state of the intestine for this study does not matter, since it has already been pushed back by the enlarged uterus. Before the examination, it is advisable not to consume the following foods:

chocolate;
cocoa, strong;
seafood;
, and other citrus fruits;
fatty and fried foods.

How do

Many people get scared when they are prescribed 2 screening during pregnancy, because they do not understand what it includes. In fact, there is nothing wrong with this study. Ultrasound. By the middle of pregnancy, the baby noticeably changes his image. Most of the indicators change, which is what experts study during the survey.

Particular attention is paid to the following parameters:

the structure of the face: the parameters of the bone of the nose, the presence of splits in the nose, ears, eyes, mouth, the stage of formation of the eyeballs;
the size of the anatomical structures of the fetus;
the level of development of the lungs;
development of internal organs: brain, heart system, respiratory system, spine, kidneys, genitourinary system;
the size and position of the placenta;
number of toes and toes;
abundance of amniotic water;
condition of the uterus, tubes, ovaries.

Few people know that looking at 2 screening during pregnancy is not only these indicators. During this period, the sex of the baby is already visible.

The data obtained by ultrasound are confirmed by hormonal analysis.

Blood test. If an ultrasound scan reveals the presence of any defect, then a biochemical blood test is necessarily prescribed. In this case, the following parameters are assessed:

the concentration of chorionic gonadotropin (hCG, hCG, hCG);
alpha-fetoprotein (AFP) composition;
the degree of free estriol (E3);
inhibin A.

The second screening during pregnancy conveys the dynamics of the development of a particular defect, because with this diagnosis they are already looking specifically at those changes that were found in the first trimester.

Decoding the results

The indicators obtained during the study help to assess the development of the baby. Changes in the level of hormones produced by the placenta may indicate defects in intrauterine growth.

The rates of the second, repeated screening during pregnancy are presented in the table:

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Deciphering of the results obtained is carried out by means of recalculation to the average indicator (MoM). This takes into account the woman's age, her complexion and even her place of residence.

The best indicator of MoM is 1. This means that the possibility of developing anomalies in the fetus is minimal.
The bottom line of the average analysis indicators should have parameters of 0.5; upper - 2. If these data are outside the scope, the pregnant woman will need a consultation with a geneticist.

The following indicators should also alert:

an increased level of human chorionic gonadotropin or MoM may indicate Down's or Klinefelter's symptom;
low hCG or MoM may indicate the presence of Edwards symptoms;
elevated E3 or MoM may indicate liver disease;
low E3 or MoM indicate placental inferiority, the fetus has no brain and there is a risk of miscarriage.

This is the data that is determined by the blood test. But 2 screening during pregnancy contains not only a hormonal examination, but also an ultrasound scan, which is necessarily included in it.

Therefore, it is also important for mummies to know what sizes of the fetus meet what terms.

Term, week	BPD (biparietal size) of the head, mm	Frontal-occipital, mm	Shin bones, mm	Shoulder bone, mm	Forearm bones, mm	Femur, mm	Head circumference, mm	Abdominal circumference, mm
16	26-37	32-49	11-21	13-23	12-18	13-23	112-136	88-116
17	29-43	38-58	14-25	16-27	15-21	16-28	121-149	93-131
18	32-47	43-64	16-28	19-31	17-23	18-32	131-161	104-144
19	36-52	48-70	19-31	21-34	20-26	21-35	142-186	114-154
20	39-56	53-75	21-34	24-36	22-29	23-38	154-186	124-164

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One of the stages of an ultrasound scan is to assess the condition of the uterus and its cervix. Normally, this figure is 3.5-4.5 cm. If the size is smaller, they diagnose ICI (isthmic-cervical inferiority).

Important! Only a combination of all indicators of the screening analysis can indicate the risk of abnormalities in the baby.

Could there be a mistake

Many expectant mothers are sure that it is impossible to draw clear conclusions based on analyzes alone. And to some extent they are right - in some cases, screening can give inaccurate results.

An error in the analysis may appear with the following facts:

Obesity of a woman. In this case, the degree of hormones increases, and if the pregnant woman is too thin, it decreases.
In Vitro Fertilization (IVF). The level of parameters will then be 10-15% below the norm.
The presence of two or more fruits. Today, there is no clear norm for multiple pregnancies.
Panic, fear. Many women are afraid of additional research, and this may affect the analysis data.
Amniocentesis. If this procedure was carried out 7 days before the screening examination, then the rate during this period is unknown.
Diabetes. The content of hormones will then be underestimated.

Pregnancy research and testing can be stressful. This can also result in a false result. Therefore, the pregnant woman must decide for herself whether she wants to receive maximum information about the health of the unborn baby.

When the decision is made in favor of screening, it is better to carry out this analysis with competent doctors, because the course of pregnancy will depend on this.

Screening is a set of measures that are aimed at identification of possible pathologies in the unborn baby... What examinations should a woman undergo? When is the second trimester screening done?

Second screening and examinations included in it

What is included in 2 pregnancy screening? The second perinatal screening is a combination of two examinations: ultrasound and biochemical, although in some cases only. Pregnant women take a blood test for the following indicators: (human chorionic gonadotropin), AFP (alpha-fetoprotein) and free estriol (E3).

On an ultrasound examination, the doctor learns the following parameters that will help determine the presence or absence of possible pathologies in the development of the baby:

thickness, location, degree of maturity and structure;
the condition of the uterus, its cervix and appendages;
amniotic fluid volume;
(the volume of the chest, abdomen and head, the length of the paired bones on each side);
development of the brain and spine;
development of the face (eyes, mouth, nose);
development of the heart and large blood vessels;
condition of vital organs: kidneys, bladder, intestines, stomach.

How long is the second screening done?

When is the second pregnancy screening done? This event takes place in the second trimester of pregnancy. The most suitable time for donating blood for analysis is 16-18 weeks, it is at this time that the screening results will be most reliable. The timing of the ultrasound screening of the 2nd trimester is at 19-20 weeks.

The second screening is mandatory for all women who are registered in the antenatal clinic, but it is especially indicated for those who have at least one of the following indications:

the parents of the unborn child are close relatives;
the mother had an infection during pregnancy;
one of the parents has a genetic disorder;
the pregnant woman has already had miscarriages;
the family has children with pathologies of the nervous system and developmental delay;
showed that the fetus has serious developmental disorders.

Some expectant mothers refuse to undergo a second screening because they believe that the results may be false positive or false negative. To do this, it is necessary to write a statement of refusal to conduct this study, which, at the request of the woman, must be provided by the attending physician.

Preparation for the survey

Preparation is necessary just before taking a blood test... To do this, the following products are excluded from the diet per day: fatty and fried foods, chocolates, fruits (citrus fruits only), fish and other seafood, cocoa. Blood is donated on an empty stomach (you cannot eat it 5-6 hours before the procedure), but you are allowed to drink a glass of water. Ultrasound examination does not require special training.

Interpretation of test results and ultrasound and the norms of the second screening

Norms of blood counts(E3, AFP and hCG) are different for each week of pregnancy:

Week of pregnancy	AFP level (U / ml)	HCG level (IU / ml)	E3 level (nmol / l)
	15-95	10000-58000	5,5-20
	15-95	8000-57000	6,5-25
	15-95	8000-57000	6,5-25
	15-95	7000-49000	7,6-27
	27-125	1600-49000	7,6-27

The doctor evaluates not only the results of blood tests, but also the data obtained during the ultrasound diagnostics. Specialist draws attention to the following points:

the size of the fetus corresponds to generally accepted norms (the child develops by age);
the face has no pathologies (the eyeballs are developed by age, the nasal bone is of normal size, there are no clefts on the face);
internal organs (kidneys, liver, heart, lungs, gastrointestinal tract, etc.) are developed by age, do not have pathologies and possible developmental disorders;
the content of amniotic fluid meets the standards;
has a normal thickness, its structure is free of signs of pathologies.

The rates of several examples of the fetus, which the doctor assesses by ultrasound screening of the 2nd trimester (16-20 weeks):

A week	Biparietal dimension (BPR) (mm)	Head circumference (mm)	Abdominal circumference (mm)	Frontal-occipital size (mm)	Femur bone length (mm)	Shoulder bone length (mm)
16	31-37	112-136	88-116	41-49	17-23	15-21
17	34-42	121-149	93-131	46-54	20-28	17-25
18	37-47	131-161	104-144	49-59	23-31	20-28
19	41-43	142-174	114-154	53-63	26-34	23-31
20	43-53	154-186	124-164	56-68	29-37	26-34

Signs of pathology at the second screening

The results of blood tests are deciphered by the attending physician. Reduced level AFP may indicate Edwards or Down syndrome, fetal death, or misidentification of the week of pregnancy. An increased level of AFP indicates malformations of the nervous system, Meckel's syndrome, death of liver cells, atresia of the esophagus, umbilical hernia.

Reduced estriol indicates the following fetal defects: intrauterine infection, adrenal hypoplasia, Down's syndrome, anencephaly, placental insufficiency, and the risk of premature birth. Elevated estriol indicates liver and kidney disease in the mother, as well as multiple pregnancies or a large fetus.

If there is any suspicion of the presence of serious pathologies, the doctor will offer the woman to carry out a procedure called amniocentesis... During it, the peritoneum is pierced and the amniotic (amniotic) fluid is taken for analysis. With the help of this test, you can confirm the presence of pathology with a probability of 99% or make sure that there is no danger to the baby. But it should be remembered that this procedure can provoke.

Sometimes the results of the second screening may not be correct. They are influenced by the following factors:

(with excess body weight, blood counts may be overestimated, with insufficient - underestimated) and the age (from 35 years) of a pregnant woman;
taking certain hormonal drugs;
abuse of drugs, alcoholic beverages and cigarettes;
chronic diseases of the expectant mother (and others);
pregnancy resulting from IVF;
multiple pregnancy.

Video about the second screening during pregnancy

We offer you to watch a video about the second pregnancy screening.

And in how many weeks did you do or will have to go through the 2nd trimester screening.

The course of the pregnancy period is subject to systematic monitoring. In the second trimester, the expectant mother is made the next. Based on the results, a conclusion is drawn up on the state of health of the woman and the child. In order to prevent intrauterine fetal pathologies, timely diagnosis is important. There is a need to study the optimal time for screening.

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Essentials of 2nd trimester screening

During the period of pregnancy, an obstetrician-gynecologist can prescribe a 2-trimester screening for a woman. It is then that the question arises, what is it and why it is being carried out. This study is designed to identify pathologies in embryonic development... The level of possible complications is determined. Among the main goals of fetal screening at this stage are:

determination of pathologies not identified during the diagnosis of the first trimester;
clarification of the reliability of the diagnoses made during the first stage of gestation;
diagnosing the level of possible complications;
identification of physiological disorders in the development of the embryo.

According to static data, the first screening study is more accurate and reliable than the second procedure.

However, isolated results cannot be the basis for a definitive diagnosis. At the end of the second screening, the dynamics of fetal development indicators is monitored.

Due to this, tendencies for the formation of conclusions are identified.

It is important to remember that this activity is not required when carrying a fetus. It is prescribed only to those patients who are at risk.

Among the factors that serve as a reason for increased attention, it is customary to include:

the patient is over 35 years old;
early irradiation of future parents;
the presence of heredity with identified pathologies;
detection of genetic pathologies in first-borns;
the course of viral diseases during the first three months of gestation;
a history of cases of spontaneous, abortive intervention and the birth of dead children;
the occurrence of conception between blood relatives;
susceptibility to harmful addictions (use of alcohol and drugs);
the use of drugs that are unacceptable when carrying a fetus;
identification of difficult working conditions.

If nothing threatens the condition of the pregnant woman, the event is not carried out. You should know that this study is a woman can pass at will.

Information about what 2 screening is during pregnancy, how many weeks it is carried out, is provided by the attending physician. During the consultation, the obstetrician-gynecologist covers the main aspects of the procedure. Due to this, exciting moments are eliminated, which sometimes constitute a danger to the condition of a pregnant woman.

Perinatal screening of the 2nd trimester allows you to determine the following pathologies:

abnormal development of the cardiovascular system;
failure in the process of building the respiratory system;
abnormal formation of the gastrointestinal tract;
defect in the spinal cord and brain;
pathological structure of the organs of the endocrine system;
defective limb development.

In case of detection of phenomena posing a danger to embryonic development, may be asked. The option for resolving the situation depends on the results obtained, as well as the individual characteristics of the mother's body.

Screening structure 2

If indicated, a woman is assigned to mandatory 2 screening during pregnancy.

What is included and what the second screening shows during pregnancy - highlights of interest to patients.

As part of the second screening event, an ultrasound examination (ultrasound) of the body is carried out and a biochemical blood test is taken.

During the ultrasound examination, the following are subject to study:

the structure and parameters of the fetal face (the eyes, nose, mouth cleft, ears are identified; the development of the eyeball is considered; the size of the nasal bone is determined);
embryo parameters (represents a fetometric analysis);
the level of embryonic development of the respiratory system;
analysis of internal fetal organs for a pathological structure(of interest are the brain and spinal cord, heart, gastrointestinal tract, urinary system);
the number of fingers on the child's upper and lower extremities;
parameters of the fetal bladder (maturity level and thickness of the placenta);
the state of the reproductive system in a pregnant woman (the area of the uterus, cervix, tubes and ovaries is analyzed);
parameters of the amniotic fluid (the fact of leakage of amniotic fluid is established or refuted).

In addition to the above aspects, as shown by ultrasound diagnostics, specified... This is achieved due to the greater severity of the primary sexual characteristics.

Diagnosis involves the transabdominal principle. The sensor of the device is in contact with the skin in the abdomen. Before starting the procedure, a gel-like product is applied.

Note! The data that ultrasound shows are supported by the results of a biochemical blood test. In the absence of violations according to the results of ultrasound markers, blood biochemistry is not surrendered.

Among the markers of fetal chromosomal pathology to be assessed during ultrasound, there are:

slowdown or absence of embryonic development;
lack of water;
ventriculomegaly;
pyeloectasia;
discrepancy with the standard value of the size of the tubular bone;
inconsistency in the parameters of the nasal bone;
cyst in the area of the choroid plexus of the brain.

Biochemical screening 2 trimester

Biochemical screening of the 2nd trimester is a blood test for the presence of specific compounds in it.

The concentration of these substances may vary depending on the identified violations.

The main purpose for which biochemical screening of the 2nd trimester is carried out is to identify:

failure in the formation of neural tubes in the brain and spinal cord;
chromosomal abnormalities (represented by Edwards syndrome and Down syndrome).

In the course of studying the composition of blood, attention is focused on the level of:

alpha-fetoprotein (AFP) indicators;
human chorionic gonadotropin (hCG);
free estriol;
inhibin A.

A blood test gives an idea of the dynamics of the condition. The diagnosis is made taking into account other research measures. Invasive measures, ultrasound diagnostic measures may be needed.

Experts are of the opinion that biochemical diagnostics is required for every pregnant woman... Even with a favorable course of pregnancy in the early stages, the expediency of conducting a study does not lose its relevance.

Preparing for screening

Preparing for the 2nd trimester screening is easy. For ultrasound diagnostics, it is customary to highlight the following list of tips:

The event can be held regardless of the time of day.
The fullness of the bladder is not able to distort the results (by the second trimester, the volume of amniotic fluid increases; the level of amniotic fluid eliminates the need to fill the bladder).
The fullness of the intestine does not play a role (by the time this organ is carried out, it is exposed to the enlarged uterus).

Blood test must give up on an empty stomach(Eating the day before the process may affect the accuracy of the results).
The exclusive use of purified water is allowed.
It is required to exclude the intake of fried food, spicy foods, flour products, sweets.
It is intended to limit allergenic foods (chocolates, citrus fruits, strawberries or other foods that cause an allergic reaction in the patient).
It is better to donate blood in the first half of the day (otherwise, a state of dizziness, nausea, vomiting may occur without the possibility of suppressing them with drugs).

The preparatory phase should be carried out with positive emotions and attitude... This is especially true when pathologies are detected after the first screening.

It should be remembered that the screening test is painless. Regardless of the patient's threshold of sensitivity, there is no discomfort. The procedure does not pose a danger to the health of a bearing child.

When is the best time to do

Screening for the 2nd trimester is an exciting stage in the course of pregnancy.

Further bearing of the fetus depends on its results. That is why the question arises when is the best time to do the procedure.

The optimal timing assumes stage from the 16th to the 20th week... Often, when asked when it is better to do this complex, experts recommend a 17-week period.

This feature is associated with a sufficient formation of the fetus. Its parameters allow you to detail individual areas of interest for assessing its condition.

Note! The accuracy of the values is directly related to such a category as the timing of the research. A correctly calculated period allows the most reliable screening of the 2nd trimester. Otherwise, the data obtained cannot be used to clarify the diagnosis.

Useful video: second screening during pregnancy

Conclusion

Screening diagnostics facilitates the process of bearing a fetus. Knowing what a second pregnancy screening is, what the specialists are looking at, frees a pregnant woman from unreasonable fears. Confidence in the condition of the fetus guarantees peace of mind for the expectant mother.

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The second screening is not a mandatory procedure; doctors prescribe it to pregnant women in order to confirm or deny the results of the first examination. The data obtained during the screening are studied carefully, checked for compliance with normal indicators, because by them parents will reliably find out how correctly and fully the child is developing in the womb.

If the results of the second study are positive, then the embryo is absolutely healthy, does not have genetic pathologies, it feels good, if negative, then, most likely, the child suffers from a serious illness. Having determined the disease, the doctor either takes over the intrauterine treatment of a small patient, or artificially causes premature birth. That is, the screening of the 2nd trimester during pregnancy can be called a responsible and important procedure, which should not be taken lightly and disregardingly.

What is the purpose of 2 screening during pregnancy?

Currently, gynecologists advise all pregnant women to undergo both the first and second screening in order to timely detect genetic abnormalities in the embryo. Each expectant mother hopes that her beloved and long-awaited baby grows and develops correctly, does not have any terrible diseases. But, unfortunately, not only strong and healthy children are born, but also babies with severe and incurable pathologies.

Screening is considered the most accurate test you can trust.

Screening of the 2nd trimester during pregnancy allows you to detect fetal malformations that are indistinguishable during the first examination, to confirm or refute the diagnosis made in the 1st trimester, to identify physical abnormalities in the child.

How is the second screening done during pregnancy?

When the 18th - 20th week of pregnancy comes, doctors advise patients to undergo 2 screening and an ultrasound scan. The examination is prescribed during this period of pregnancy for a reason, since it is at this time that it is convenient to study the embryo. The first screening, carried out in the middle of the first trimester of pregnancy, does not provide accurate information about the physical condition of the child in the womb, but only shows how correctly embryonic development is proceeding. But on the other hand, the second screening and ultrasound at week 20 can be very valuable data on the health of the fetus for the gynecologist. Having received negative results of the study, the doctor offers parents two options for further actions: either to give birth to a sick child, or, before it is too late, to agree to an abortion. Translated from English, screening is sifting, that is, calculating the likelihood of having children with certain deviations. The most popular screening program is PRISCA, or Perinatal Risk Assessment. It usually includes three studies.

Biochemical triple test. During the 2nd trimester of gestation, venous blood is taken from a pregnant woman to check the content of markers of AFP, hCG, estriol. AFP, or alpha-fetoprotein, is a protein synthesized by the liver and digestive tract of the fetus. HCG, or human chorionic gonadotropin, is a hormone produced in the embryonic membranes that is present only in the blood of pregnant women. The sex hormone estriol is produced by the ovarian follicular apparatus. A biochemical test allows you to determine the likelihood of developing such severe chromosomal diseases as Down syndrome and Edwards syndrome in the embryo. For a pregnant woman, the study is completely safe, the concentration of AFP, hCG, estriol is simply calculated in the blood, no manipulations are performed on the woman's body.
Ultrasonography. Screening ultrasound is more accurate and detailed than conventional ultrasound. The medical specialist very carefully examines the image of the embryo on the monitor of the ultrasound machine. The doctor can find in the embryo both minor physical defects that can be easily cured with medication or surgery, as well as serious developmental abnormalities that cannot be eliminated. Usually, using ultrasound at the second screening, it is easy to diagnose a hernia in the diaphragm, clubfoot, cleft lip, cleft palate, shortening of long bones, deformation of the fingers and many other pathologies.
Cordocentesis. This procedure is not required as part of the second screening. But if a blood test and an ultrasound scan show the presence of certain abnormalities, then cordocentesis is still recommended. The operation is quite complicated, but it is it that allows you to find out what is wrong with the baby in the womb. A special needle is inserted into the belly of a pregnant woman, with the help of which the blood of the embryo is taken from the umbilical cord. The collected blood is sent to the laboratory for analysis, according to the results of which the doctor makes an accurate diagnosis of the embryo. But I must say that cordocentesis is an unsafe procedure. Two out of a hundred women have a miscarriage after surgery. Often the needle leaves behind a hematoma, which, however, quickly resolves. One woman in a hundred after the procedure becomes infected.

What diseases can be found in the embryo at the second screening?

Many women wonder if it is really necessary to do 2 screening during pregnancy. Research is not cheap at all. But will the money spent pay off? In fact, screening for the second trimester of pregnancy should not be underestimated as it provides parents with important information about their baby developing in the womb. Based on the results of the study, the family decides whether to keep the baby or have an abortion. If the embryo is seriously and terminally ill, then it is better not to torture him, but to artificially terminate the pregnancy. Until the end of the second trimester, an abortion is still allowed. Some mothers are concerned about the moral side of the issue. In this case, you should think about how difficult it is to raise and educate children with disabilities. Do your parents agree to take on this burden for life? Or is it still better to postpone the birth of a child? Usually, second trimester screening is performed to detect such abnormalities in the development of the embryo: neural tube defect, Down syndrome, Edwards syndrome, Patau syndrome.

Neural tube defect. On the twentieth day of intrauterine existence, the neural plate appears in the embryo. After a few days, it rolls up into a tube - the rudiment of the central nervous system, including the brain and spinal cord. The formation of the tube is very slow, sometimes the plate does not close completely or straightens out. In this case, the most severe fetal malformations occur: anencephaly, cephalocele, meningocele. Anencephaly, or pseudocephaly - the absence of the cerebral hemispheres, temporal and occipital parts of the skull. The midbrain and diencephalon are deformed, the eyes are bulging, the tongue is unnaturally long, the neck is short, the upper part of the head is covered with a dense membrane, instead of the skull, which is dotted with blood vessels. Cephalocele, that is, splitting of the skull - the release of brain tissue to the outside through defects in the cranium. Meningocele is a median spinal anomaly in which the contents of the spinal canal are not completely closed.
Down Syndrome. This chromosomal disorder, also called trisomy, occurs at the time of conception. In a sick embryo, the karyotype includes not 46 chromosomes, as in a healthy person, but 47. In Down syndrome, the twenty-first pair of chromosomes is actually a three, not a pair. This genetic abnormality occurs when an egg or sperm cell carries an extra chromosome during fertilization. Newborn babies with Down syndrome have a small head, a flattened face, deformed ears, a flat nose, slanting eyes, a short neck, an always open mouth, short limbs. The onset of the disease does not depend on the race, lifestyle, health, age of the parents. It is impossible to predict and prevent a chromosomal mutation.
Edwards syndrome. This disease, like Down's syndrome, occurs during conception, is the result of a change in the karyotype. Only the extra third chromosome is located not in the twenty-first, but in the eighteenth pair of chromosomes. Newborn babies with Edwards syndrome are weak, sore, underweight and underweight. They look premature, but are born late. Sick children have short sternum, deformed ribs, dislocated hips, clubfoot, twisted fingers, papillomas on the skin. Babies with Edwards syndrome have a specific head structure, they have a low forehead, a short neck, underdeveloped eyeballs, a bulging nape, low-set ears, deformed auricles, a small mouth, and a cleft in the upper lip. With this disease, almost all systems and organs do not work correctly, heart defects, intestinal obstruction, renal failure, hernias in the groin area, fistulas in the esophagus, and diverticula of the bladder occur. Sick children rarely live to see their first birthday.
Patau Syndrome. This disease is characterized by the presence of serious congenital defects. The body weight of newborns diagnosed with this disease does not exceed 2.5 kg. Children have developmental disorders of various parts of the central nervous system, moderate microcephaly, pathologies of the visual system (corneal opacity, coloboma, microphthalmia, etc.), polydactyly, and developmental disorders of the hands. Children with Patau syndrome often have a sloping low forehead, narrow eye slits, a wide base of the nose and a deep bridge of the nose, anomalies of the auricles, a short neck, and clefts in the palate and upper lip. More than half of babies suffer from malformations of the heart muscle - abnormalities in the development of cardiac septa and the position of blood vessels are common. Children are diagnosed with disorders in the development of pancreatic tissues, embryonic hernia, duplication or enlargement of internal organs (spleen, kidneys, etc.), malformations of the organs of the reproductive system. Cysts, increased lobulation of the cortical tissue of the kidneys may be present. The mental retardation characteristic of the joint venture is noted. These severe developmental pathologies prevent the majority of infants (95%) with Patau Syndrome from surviving for more than a few weeks or months. In rare cases, it is possible to maintain the life of such patients for several years. In developed countries, there is a tendency to extend the life expectancy of children with Patau syndrome to five years.

It is worth noting that, although the above pathologies occur extremely rarely, they are distinguished by cunning and unpredictability. It is impossible to prevent chromosomal mutations, they appear during conception, do not heal, do not disappear on their own, remain for life. Sick children cannot live fully, suffer from their own handicap, depend on loved ones, and are disabled. The bad news is that diagnosing chromosomal diseases in an embryo in the womb is a difficult task for medical professionals.

Even if a second screening is carried out using the most accurate and modern methods, it is not always possible to make a reliable and final diagnosis. In most cases, doctors simply tell parents how likely they are to have a child with disabilities. And the family is already deciding whether to keep the pregnancy or not.

How long does it take for the second screening?

It is imperative not to miss the timing of the second screening. Usually, doctors recommend that patients undergo examination not earlier than 16 weeks of pregnancy, but not later than 20 weeks. If you do the screening early, then if a pathology is detected in the embryo, it is not so dangerous to have an abortion. If you go through the examination later, you can get more accurate and reliable results.

Medical experts believe that the most optimal timing for the second screening is 17-19 weeks of pregnancy. At this time, it is convenient to study the state of the embryo in the womb, and you can still artificially terminate the pregnancy.

How do I prepare for the second screening?

Preparing for a second screening is usually not difficult, as women already have experience with the first screening. Morally difficult can only be for mothers who have not received encouraging results during the first trimester screening. It is not easy to relieve anxiety and a bad feeling, but you need to try to do it. Before the second examination, the bladder and intestines may not be emptied, the fullness of the organs with urine and feces does not affect the ultrasound results. The day before the screening, foods that can cause allergies should be excluded from the menu: citrus fruits, chocolate. On the day of donating blood for analysis, you should starve, as food intake can make false laboratory results.

How is the diagnosis made from the second screening?

Screening of the 2nd trimester during pregnancy is carried out within one day. After the examination, the doctors prepare the test results for several weeks. As a result, a medical report comes into the hands of parents, consisting of a rather impressive list of digital data, which is not easy for an uninformed person to understand. By what numbers deviate from normal values, doctors determine what kind of disease the embryo suffers from in the womb. An excess or insufficient amount of AFP, hCG, or estriol in the mother's blood indicates a specific fetal anomaly. Normal 2 screening and ultrasound results should be as follows:

16 weeks pregnant

The weight of the embryo is 100 g.
Body length - 11.6 cm.
Tummy circumference - 88 - 116 mm.
Head circumference - 112 - 136 mm.
Frontal-occipital size - 41 - 49 mm.
The biparietal size is 31 - 37 mm.
The length of the shin bone is 15 - 21 mm.
The length of the femur bone is 17 - 23 mm.
The length of the forearm bone is 12 - 18 mm.
The length of the shoulder bone is 15 - 21 mm.
Amniotic fluid index - 121.
The content of alpha-fetoprotein is 34.4 IU / ml.
The estriol content is 4.9 - 22.7 nmol / l.

17 weeks pregnant

The weight of the embryo is 140 g.
Body length - 13 cm.
Tummy circumference - 93 - 131 mm.
Head circumference 121 - 149 mm.
The frontal-occipital size is 46 - 54 mm.
The biparietal size is 34 - 42 mm.
The length of the shin bone is 17 - 25 mm.
The length of the femur bone is 20 - 28 mm.
The length of the forearm bone is 15 - 21 mm.
The length of the shoulder bone is 17 - 25 mm.
Amniotic fluid index - 127.
The content of chorionic gonadotropin is 10 - 35 thousand.
The content of alpha-fetoprotein is 39 IU / ml.
The estriol content is 5.2 - 23.1 nmol / l.

18 weeks pregnant

The weight of the embryo is 190 g.
Body length - 14.2 cm.
Tummy circumference - 104 - 144 mm.
Head circumference - 131 - 161 mm.
The frontal-occipital size is 49 - 59 mm.
The biparietal size is 37 - 47 mm.
The length of the shin bone is 20 - 28 mm.
The length of the femur bone is 23 - 31 mm.
The length of the forearm bone is 17 - 23 mm.
The length of the shoulder bone is 20 - 28 mm.
Amniotic fluid index - 133.
The content of chorionic gonadotropin is 10 - 35 thousand.
The alpha-fetoprotein content is 44.2 IU / ml.
The estriol content is 5.6 - 29.7 nmol / l.

19th week of pregnancy

The weight of the embryo is 240 g.
Body length - 15.3 cm.
Tummy circumference - 114 - 154 mm.
Head circumference 142 - 174 mm.
The frontal-occipital size is 53 - 63 mm.
The biparietal size is 41 - 49 mm.
The length of the shin bone is 23 - 31 mm.
The length of the femur bone is 26 - 34 mm.
The length of the forearm bone is 20 - 26 mm.
The length of the shoulder bone is 23 - 31 mm.
Amniotic fluid index - 137.
The content of chorionic gonadotropin is 10 - 35 thousand.
The content of alpha-fetoprotein is 50.2 IU / ml.
The estriol content is 6.6 - 38.5 nmol / l.

20th week of pregnancy

The weight of the embryo is 300 g.
Body length - 16.4 cm.
Tummy circumference - 124 - 164 mm.
Head circumference - 154 - 186 mm.
Frontal-occipital size - 56 - 68 mm.
The biparietal size is 43 - 53 mm.
The length of the shin bone is 26 - 34 mm.
The length of the femur bone is 29 - 37 mm.
The length of the forearm bone is 22 - 29 mm.
The length of the shoulder bone is 26 - 34 mm.
The amniotic fluid index is 141.
The content of chorionic gonadotropin is 10 - 35 thousand.
The content of alpha-fetoprotein is 57 IU / ml.
The estriol content is 7.3 - 45.5 nmol / l.

If the fetus has Down syndrome, then the content of hCG in the blood of a pregnant woman is high, and AFP and estriol are low. In Edwards syndrome, the concentration of all substances is below normal. With a neural tube defect, chorionic gonadotropin is normal, and estriol and alpha-fetoprotein are high. Also, a high content of AFP can mean a violation of the development of the spinal cord in the embryo, and a low one - Meckel-Gruber cider, liver necrosis, occipital hernia, spina bifida. If the concentration of estriol in the blood is very low, then a miscarriage is likely. But if the study is negative, parents should not despair. Doctors, when they do 2 screening during pregnancy, warn that it is impossible to make a 100% accurate diagnosis. It happens that, despite the unfavorable forecasts of doctors, women give birth to healthy and full-fledged children.

Why does second trimester screening sometimes give false results?

Physicians are people too, and they sometimes make mistakes. When making a diagnosis, doctors are guided by the numerical indicators of the norm, but the body of each woman is individual, and even significant changes in the content of AFP, hCG, estriol in the blood do not always indicate pathology. You should not try to figure out the results of the examination on your own, let alone diagnose the child in the womb. It is better to entrust this lesson to a gynecologist. It is not easy to decipher the final data of the second screening, and an experienced medical specialist, at one glance at the numbers, perfectly sees the whole situation. It happens, albeit rarely, that research shows false results, due to certain reasons. Therefore, before screening, the doctor must interview and question the patient in order to weed out possible factors that affect the veracity of the examination indicators. A false result is possible in the following cases:

with multiple pregnancies;
at conception by the IVF method;
with obesity or, conversely, underweight;
with diabetes mellitus;
with an incorrectly determined period of pregnancy.

Is it worth doing a 2nd trimester screening?

Whether or not to undergo a second screening is a personal decision. The mom-to-be must accept it on her own.

Sometimes the reluctance to undergo a second trimester screening is associated with inner experiences. These experiences may not be just like that, because it happens that screening studies give erroneous results and identify threats to the development of pathologies in the fetus, which is developing quite normally.

False results make the mother-to-be nervous and worried about the baby for the rest of the gestation period. And this, in turn, leads to a negative course of pregnancy and can affect the health of the expectant mother and fetus. Fortunately, the situation is far from hopeless. If a pregnant woman is afraid of invasive diagnostic methods that provide the most reliable information about the presence or absence of abnormalities, she can resort to safe non-invasive prenatal DNA tests.

If a woman does not fall into a risk group or does not have complications during pregnancy, then the leading doctor proposes to undergo only an ultrasound procedure. In Russia, the second screening has not been practiced for about two years. However, the absence of negative results in the first trimester does not guarantee that there are no risks in the second trimester. Of course, it is inappropriate to prescribe additional tests for every woman who is expecting a baby. This only provokes women to worry and waste family funds.

The choice for the family, if the results of the 2nd screening and ultrasound were poor, is not great: to save the life of a sick child or to agree to an abortion for medical reasons, while the term still allows this operation. Such a decision cannot be considered a moral crime, since the reasons for it are quite reasonable. A family that, due to moral or material reasons, cannot take care of a child with serious disabilities, will be able to prepare for a new pregnancy in the future and give birth to a healthy child. This is much wiser than subjecting yourself and your little one to life's tests.

There are also families that treat the baby as a divine gift, so it doesn't matter how he is born. For such couples, termination of pregnancy is an even greater disaster than the birth of a baby with pathologies. Therefore, families who are happy to give their baby their love and protection can safely refuse screening.

Under all circumstances, the conclusion must be made soberly, and not under the influence of emotion. If you are in doubt about whether a second trimester screening is necessary and when to undergo examinations, it is better to consult with your doctor, based on the data of previous tests.

In what cases is it necessary to do 2 screening?

If a woman feels well, pregnancy is not accompanied by complications, then it is not necessary to do a second screening. But if the expectant mother wants to undergo an examination to make sure that everything is in order with the precious baby in the stomach, then the doctors have no right to refuse her. But there is a category of pregnant women who cannot ignore second trimester screening, since there is a high risk of severe malformations in the embryos they carry. Mothers must be examined:

over 35 years old;
having bad heredity;
recovered from a viral disease at the beginning of pregnancy;
married to a close relative;
addicted to drugs;
abusing alcoholic beverages;
working in hazardous conditions;
taking strong medications;
previously had an abortion;
survivors of a miscarriage or stillbirth.

How is second trimester screening done?

The second trimester of pregnancy for many women is marked by screening, a triple test for fetal chromosomal abnormalities. This study is considered slightly less informative than the one that is conducted at the end of the first trimester. But nevertheless, biochemical screening of the 2nd trimester and ultrasound can and are considered as objective data for calculating risks and even making an accurate diagnosis.

What is this study, what is its information content, can there be errors? Screening of the 2nd trimester is a complex of medical measures, a blood test from a vein and an ultrasound scan, the results of which are entered into a computer program that calculates the risks of Down syndrome, Edwards, Patau, Turner, triplodia and others.

In this case, the decoding of the results of biochemical screening of the 2nd trimester is issued by the program in the form of a quantitative risk. For example “Down syndrome - 1: 1800. And this means that one woman out of 1800 of the same age, with the same features of the course of pregnancy, the results of ultrasound and blood tests, gives birth to a child with this pathology.

Since many women simply do not take risk numbers seriously, they decide to undergo only part of this examination. Namely, ultrasound screening of the 2nd trimester, which can clearly show malformations of organs and systems of the fetus, suggest that he has a genetic disease based on some markers, such as shortening of the nasal septum or the absence of the phalanx of the little finger. In addition, prenatal screening of the second trimester makes it possible to diagnose overt congenital malformations of the face, heart, stomach, brain and spinal cord, urinary system, and honesty of the kidneys. Many of these pathologies are indications for artificial termination of pregnancy, since they cannot be treated with surgery and make the fetus unviable. Some markers can also be identified that indicate genetic abnormalities, but not always. For example, renal pyelectasis, hyperechoic inclusions in the heart, hyperechoic intestines, etc. These markers require re-examination. And blood screening of the 2nd trimester is very useful in this case. But even if the screening results are good, the ultrasound is repeated after 2-3 weeks. It is highly desirable to do an ultrasound of an expert class, to consider problem areas, including in 3D mode, so the information obtained will be more accurate.

Screening of the 1st trimester and the second screening during pregnancy differ in the methods of carrying out. So, at the first screening, it is very important to accurately observe the timing of the blood test and ultrasound. This must be done on the same day. And the timing of the second screening during pregnancy for ultrasound and biochemical analysis is different. So, the expectant mother donates blood for alpha-fetoprotein (AFP), free β-hCG and extriol for a period of 16-18 weeks. It is imperative to comply with this deadline! But ultrasound is most informative for a period of 20 weeks. Moreover, only biochemical screening is effective no more than 70%. That is, about 30% of favorable blood test results turn out to be false negative, those who took them will have children with Down's or Edwards syndrome.

At the same time, adverse 2-trimester screening results are usually indications for invasive diagnostics. For longer periods, this is either amniocentesis (at 16-20 weeks) or cordocentesis (more than 20 weeks). Moreover, amniocentesis is less dangerous in terms of complications in the form of spontaneous late miscarriage or premature birth. Sometimes it happens that the screening of the 2nd trimester of the norm by ultrasound shows, and a child with the syndrome is born ... The reason for this is the absence of any markers of chromosomal pathologies, poor visualization during ultrasound examination, and sometimes even the doctor's inattention.

Many women are poorly versed in how to do ultrasound screening for the 2nd trimester, blood tests are taken. And they are trying to pass these examinations on their own. They make mistakes in the timing, get the results of blood tests without calculated risks - all this makes the screening completely unreliable. After all, decoding the results of second trimester screening is the task of a special computer program, and not of a pregnant woman or even her attending physician. By the way, it is not at all necessary for all expectant mothers to perform a biochemical blood test in this case. Coupons are usually issued only to those who had a poor first screening, the second screening during pregnancy is of a clarifying nature.

It is imperative to undergo this examination also for women over 35-40 years old, and regardless of whether they have children of their own, suffering from alcoholism and (or) drug addiction, surviving a severe viral disease in the early stages of gestation, those who already have children with chromosomal pathology, with a closely related marriage, as well as taking medications that have a toxic effect on the fetus.

Facts such as IVF, multiple pregnancies, diabetes mellitus in the mother, too little or too large a woman's weight, and some bad habits can influence the accuracy of the results.