Chorionic villus biopsy and its consequences. What should you know about chorionic villus sampling? Chorionic presentation: precautions

Chorionic biopsy or chorionic villus biopsy is one of the modern invasive methods of direct prenatal diagnosis. It is intended for collecting tissue samples of embryonic origin with their subsequent molecular genetic, cytogenetic, and biochemical studies. Chorionic biopsy is performed strictly according to indications and only at certain times of gestation by specialists who have the appropriate certificate and experience.

What is chorion and what does its study provide?

The chorion is the villous extra-embryonic outer membrane. It is formed 7-12 days after conception from the fusion of cells of the extraembryonic mesoderm and trophoblast. And from the end of the first trimester of pregnancy, the chorion gradually transforms into the placenta. At the same time, its tertiary well-vascularized villi form branches and form cotyledons (structural and functional placental units). In this case, direct contact between the maternal and fetal blood circulation finally ceases.

The main functions of the chorion include:

Separation of the embryo from the tissues of the uterine wall. In this case, the chorion with its villous part is in contact with the decidua (formed from the endometrium). And its smooth part is the second layer of that part of the fetal sac, which is called the fetal membrane.
Ensuring the exchange of substances and gases between the embryo and maternal blood (excretory and trophic functions). This is possible due to the growth of chorionic villi into the walls of the spiral arteries of the uterine wall.
Protection of the embryo from infectious agents and toxins. This barrier begins to work fully from the 10th week of gestation, when the formation of the placenta begins. In the early stages of pregnancy, chorionic villi are not yet able to adequately filter substances contained in a woman’s blood. Therefore, this period is characterized by a fairly high probability of occurrence of disorders of embryogenesis of a toxic and infectious nature.

Chorion tissues are of embryonic origin. So their genetic material is basically the same as that of an embryo. And taking a small part of the chorion for research does not affect the process of organogenesis of the unborn child and in 97-99% of cases is not critical for prolonging pregnancy. This is what is used when performing chorionic villus biopsy for a variety of hereditary anomalies.

How informative is chorionic villus biopsy?

Currently, chorionic villus biopsy followed by examination of the resulting material makes it possible to identify almost 3,800 different diseases. Moreover, the result obtained has a high degree of reliability.

The diagnostic capabilities of chorionic biopsy include identifying the following groups of diseases:

Various chromosomal abnormalities (Down, Edwards, Turner, Klinefelter, Patau syndromes, etc.).
Monogenic diseases with different types of inheritance.
Enzymatic pathologies - for example, phenylketonuria, Lesch-Nyhan syndrome, citrulinemia, arginine succinic aciduria.
Thalassemia and other hemoglobinopathies.
Numerous lysosomal storage diseases. These include sphingolipidoses (Fabry, Crabbe, Landing, Tay-Sachs, Niemann-Pick diseases, adrenoleukodystrophy, etc.), carbohydrate metabolism disorders (glycogen storage diseases, Pompe disease), glycosaminoglycan metabolism disorders (various mucopolysaccharidoses), and glycoprotein metabolism disorders.

The reliability of identifying these diseases is very high. Diagnostic errors may be associated with technical errors when collecting material, when uterine tissue is also included in the chorionic villus biopsy. But this is rare. False-positive test results for mosaicism are also possible, when this chromosomal pathology occurs only in chorion cells.

Diagnostic errors occur in no more than 4% of cases. Moreover, they are usually associated with overdiagnosis, rather than false negative results. So the method as a whole has high accuracy. But it also has some limitations. For example, a chorionic villus biopsy will be uninformative if the embryo has defects in the formation of the neural tube that are not associated with pathology of the genetic material.

Of course, the diagnostic capabilities of the method depend on the technical equipment of the medical genetic center and the availability of certain reagents in it. Therefore, if a certain uncommon anomaly is suspected, the doctor must first clarify whether the necessary research can be carried out in this laboratory. If necessary, the material is sent to another region in compliance with the necessary transportation conditions.

In what cases is research carried out?

Chorionic villus biopsy is not an ordinary test. It is carried out only if there are certain indications, if non-invasive diagnostic methods do not provide the necessary and reliable information. The decision on such manipulation is usually made by a medical commission and requires the mandatory informed consent of the woman. She has the right to refuse the proposed diagnosis, which is not the basis for any subsequent restrictions on the scope of the prescribed examination and treatment.

Indications for chorionic villus biopsy include:

Previous birth of a woman with a child with disorders caused by any gene or chromosomal abnormalities. The fact of stillbirth or death of a newborn in the first few days is also taken into account.
The presence of people in the family with hereditary diseases, even if they are not first-degree relatives. Confirmed carriage of a recessive pathological gene (including sex-linked) in at least one of the parents.
An unfavorable result of the first mandatory prenatal screening (ultrasound and biochemical examination) with an identified high risk of certain chromosomal diseases in the embryo.

A relative indication is also the age of a woman over 35 years old. After all, this is associated with an increased likelihood of spontaneous critical mutations, especially in the presence of other factors predisposing to this.

Contraindications

A planned chorionic villus sampling may be delayed or canceled in the following cases:

high risk of threatened miscarriage - for example, with multiple myomatosis or the presence of a large fibroid node with significant deformation of the uterine cavity;
already diagnosed threatened abortion (high uterine tone, appearance of bloody discharge from the genital tract);
the woman has fever, a current acute infection or a clinically significant exacerbation of a chronic infectious and inflammatory disease;
features of the attachment of the chorion, which leads to its inaccessibility for biopsy;
dermatitis or infectious lesion of the skin and subcutaneous tissue on the anterior abdominal wall diagnosed in a woman (with a planned transabdominal chorionic villus biopsy);
infectious nature (in the case of transcervical chorionic biopsy);
clinically significant deterioration in the general somatic condition of the pregnant woman.

Time frame for the study

The timing of chorionic villus biopsy is determined by the period when the embryo’s main organs and systems are already formed, its membranes are quite large, but the placenta has not yet fully formed. Therefore, the procedure is most often performed between 10 and 13 weeks of gestation.

In addition, during this period the risk of biopsy-provoked spontaneous abortions is significantly lower than in earlier periods. And the doctor usually already has the result of the first basic prenatal screening, which provides indicative information about the presence of signs of some of the most common chromosomal diseases.

At later stages, the chorion is gradually transformed into the placenta. Taking a sample (part) of this formation is also possible. But this is a different test called placentocentesis or placental biopsy.

A combination of several techniques is also possible. For example, sometimes chorionic villus biopsy is performed using the same access (simultaneously). This makes it possible to significantly increase the information content and reliability of prenatal diagnosis, as it also makes it possible to obtain information about abnormal development of the fetus or its infection.

Types of research

Currently, 2 types of chorionic biopsy are practiced:

Transabdominal, when access to the uterine cavity and fetal membranes is achieved by puncturing the anterior abdominal wall.
Transcervical - through the cervical canal, without violating the integrity of the uterine wall.

Transabdominal chorionic villus biopsy can be single-needle or double-needle.

Currently, the transabdominal technique is most often preferred. In this case, the specialist gains access to the chorion located along the front or side walls at any level. But when attaching the embryo along the posterior surface of the uterus, it is advisable to use the transcervical technique.

How is chorionic villus sampling performed?

Before the procedure, the woman is given a preliminary examination. It includes general clinical blood and urine tests, analysis for major infections, and a vaginal smear to determine the degree of purity. The procedure is also mandatory, despite the first screening being recently carried out. Often, sonography is performed on the day of the biopsy. In fact, the specialist first assesses the condition of the uterus and the position of the embryo, after which he begins the procedure for collecting biomaterial.

Although chorionic villus sampling is an invasive procedure, it is performed in the vast majority of cases without the use of anesthesia. In the case of the transabdominal technique, application anesthesia can be used, if necessary, to reduce discomfort at the time of skin puncture.

Chorionic villus biopsy is performed under mandatory ultrasound control of the position of the puncture needle. In this case, the free-hand method or a special puncture adapter can be used. 1-2 hours before the examination, the woman is recommended to drink several glasses of water, which will fill the bladder and thereby significantly improve visualization of the uterine cavity.

In general, the procedure (for the transabdominal option) includes:

Antiseptic treatment of the area on the abdomen that is supposed to be used for puncture.
Linear puncture of the tissues of the anterior abdominal wall and uterus with immersion of the tip of the puncture needle into the myometrium.
Changing the position of the needle so that it is directed parallel to the chorionic membrane.
Immersion of the needle into the chorionic tissue, removal of the mandrin and gentle aspiration of the sample. In this case, to collect the material, a syringe with a transport medium is attached to the outer contour of the needle. If a two-needle technique is used, only the inner needle of a smaller diameter is immersed into the chorion. A thicker guide needle acts as a trocar for the initial puncture of the abdominal wall and uterine wall.
Removing the needle, covering the puncture site with an aseptic bandage, ultrasound monitoring of the embryo's heartbeat and the condition of the uterine wall.

During transvaginal chorionic biopsy, material is collected using a flexible thin catheter with a mandrel. In this case, the cervix is fixed by grasping it with bullet forceps. The tip of the catheter is also inserted into the chorion parallel to the uterine wall under ultrasound guidance.

Usually the entire procedure takes no more than 30 minutes. Although, when the chorion is located on the side walls of the uterus or in its corners, technical difficulties with access are possible, which will increase the duration of the biopsy.

For a full diagnosis, it is necessary to obtain at least 5 mg of chorionic tissue. The optimal biopsy volume is 10-15 mg. This will allow you to conduct several types of research if necessary.

Possible risks of the procedure

The invasiveness of this technique is the main risk factor for the development of possible complications and consequences. True, they occur infrequently and are not always associated with technical errors in the biopsy performed or insufficient experience of the doctor. In general, according to medical statistics, no more than 4-5% of patients experience serious complications.

Possible negative consequences of chorionic villus sampling include:

Spontaneous abortion () during the first 5-7 days after the procedure. Diagnosed in 2–2.5% of cases. The risk of induced miscarriage is higher with transcervical chorionic villus biopsy.
Bloody discharge from the genital tract, which occurs mainly in women after transcervical chorionic villus biopsy. They may be associated not so much with damage to the chorion itself, but with injury to the cervix from bullet forceps. Nevertheless, the patient's complaints of bleeding require clarification of the source of bleeding with the obligatory exclusion of a threatened abortion. About 20-25% of women after transcervical chorinobiopsy experience this phenomenon. And in most cases, it stops on its own and without any negative consequences.
Formation of retrochorial hematoma. It is considered a factor that increases the likelihood of abortion. But in most cases, such a hematoma resolves by the 16th week of gestation and does not affect the development of the fetus. And when it breaks into the uterine cavity, a woman may experience brownish-bloody, light discharge from the genital tract.
Development . It is a rare complication. Many authors point out that there are no significant differences between the frequency of post-biopsy and spontaneous chorioamnionitis.
Violation of the integrity of the fetal membranes, which is most likely with transcervical chorionic villus biopsy. It is fraught with leakage of amniotic fluid and the development of infectious complications.
When performing chorionic biopsy in the early stages of gestation, congenital transverse amputations of the limbs are possible due to trophic disorders in the area of intervention. By the end of the 1st trimester, the risk of developing this complication is leveled out. That is why, since 1992, chorionic villus biopsy has been performed no earlier than the 8th week of gestation, preferably from the 10th week.
Increased serum α-FP levels. It is transient in nature, does not require drug correction and usually resolves by 16-18 weeks of gestation. However, it is necessary to take into account the risk of such a consequence when prescribing biochemical screenings in the 2nd trimester in order to exclude false-positive results for the likelihood of defects.
Alloimmune cytopenia in the fetus, which is possible with. To prevent this, it is practiced to administer anti-Rhesus immunoglobulin to previously non-sensitized women with Rh-negative blood, if the father of the child is Rh-positive. The drug is usually administered in the first 48-72 hours after chorionic villus biopsy.

In general, despite its invasiveness, this diagnostic technique rarely leads to the development of truly severe complications. Of course, a lot depends on the doctor’s skills and the pathology present in the woman and/or embryo.

What to do after chorionic villus biopsy

After a chorionic villus biopsy, a woman is usually prescribed preventive therapy aimed at maintaining pregnancy. In this case, it is recommended to temporarily limit physical activity, avoid heavy lifting and sexual intercourse. Drugs can also be used to reduce the tone of the uterus, and the dose of hormonal drugs received by the pregnant woman can be increased.

According to indications, antibacterial and hemostatic therapy is carried out, and anti-Rhesus immunoglobulin is administered. The woman is also prescribed a control ultrasound to assess the condition of the fetus.

Biopsy results are usually received in 10-14 days. This period is explained by the need to transport the biomaterial to the laboratory, wait for cell growth in a special environment, and conduct a series of studies. But the first tentative results may be known already in the first few days.

If the result is negative, the woman continues to carry the pregnancy. She no longer has to worry about the presence of chromosomal and gene abnormalities or storage diseases in the fetus. If a positive answer is received from the laboratory, the pregnant woman is faced with a choice: to prolong or terminate this pregnancy. The decision remains hers; the conclusion of the medical commission on the advisability of an abortion for medical reasons is advisory in nature.

If necessary and the availability of an appropriate specialist, a woman and her husband are given the opportunity to receive help from a psychologist. In addition, in some cases, it is advisable to conduct genetic counseling for other relatives of reproductive age. This will make it possible to clarify in advance the risk of having a child with a corresponding anomaly.

If the pregnancy continues, the issue of the place and method of delivery is subsequently decided, and a plan for the examination and management of the newborn is drawn up.

Diagnostic testing that detects chromosomal abnormalities and other inherited diseases of the fetus is called chorionic villus sampling. Testing is recommended by a family doctor if potentially dangerous diseases are traced on the paternal or maternal side.

Diagnosis is carried out in the early stages of pregnancy by invasive examination of the tissues of the future placenta. The purpose of testing is to identify chromosomal abnormalities or monogenic hereditary diseases - hemophilia, cystic fibrosis, hereditary pancreatitis, Marfan syndrome, achondroplasia, congenital cataracts, mental retardation, Down syndrome and many other inherited diseases.

Chorionic villus biopsy is an invasive method of prenatal diagnosis with invasion of the uterine cavity and selection of biological material - chorionic villi. The essence of the study is to obtain a small piece of tissue from the future placenta. The tissue cells are unique in that they contain the same chromosomes as the baby developing in the womb.

The identity of the cells of the placenta and the fetus beginning its development makes it possible to determine already in the early stages of pregnancy whether the child at birth will be burdened with hereditary diseases or not.

Did you know? Chorionic villus biopsy allows for chromosomal analysis of the cells of a child developing inside the womb, without affecting the fetus itself.

Who is the procedure indicated for?

Women who became pregnant at the age of 35 (or older);
The results of the first screening test indicate the risk of having a child with Down syndrome;
In the case of early determination of the child’s gender, since hereditary hemophilia or Duchenne dystrophy was observed on the paternal line;
When relatives already have the birth of a child with Down syndrome or other hereditary diseases associated with an abnormal set of chromosomes, as well as a genetic disorder;
Detection of the development of a congenital defect in a developing fetus using ultrasound examination.

Unfortunately, diagnostic testing is not carried out in every clinical laboratory. In addition, chorionic villus biopsy is quite an expensive pleasure, and not every family budget can afford it. Having health insurance covers part of the costs for women over 35 years of age, while other potential patients are forced to look for alternative research methods.

How and at what time is chorionic villus biopsy performed?

The optimal time for testing for the presence of defective chromosomes is considered to be the period from the 9th to the 12th week of pregnancy inclusive. The procedure is carried out under the control of ultrasound equipment. The selected biomaterial is processed and examined for two or three, and extremely rarely – seven days.

A specialist takes a tiny piece of tissue from the point of attachment of the chorion to the uterine wall. A few cells are enough to conduct a full study of the biomaterial.

The material is collected using one of two existing methods for conducting diagnostic research.

Transcervical method(transcervical modum) involves inserting a thin catheter through the cervix and bringing it to the placenta protrusion site. The process of collecting biomaterial is monitored using ultrasound. The chorionic villi are gently selected with a catheter, after which the catheter is removed from the body. This method of taking a chorionic villus biopsy is considered the most common.
Transabdominal method(transabdominal modum) research consists of taking a puncture. Under local anesthesia, the abdomen and uterine wall are pierced with a thin long needle, which is brought to the placenta under ultrasound control and chorionic villi are collected. After the manipulation, the needle is removed.

The first method allows you to sample a larger volume of material, and the analysis result is prepared faster than with the second method.

What do chorionic villus biopsy results show?

Receiving a negative test result indicates that there is no abnormal development of the fetus at the genetic or chromosomal level. But the birth of a completely healthy child is not guaranteed, nor is the possibility of further occurrence of certain problems relating to his health.

If a serious pathological disease is confirmed (a positive test result), there is a short period of time during which the most important decision must be made - to continue or terminate the pregnancy.

Medical abortion(artificial termination of pregnancy) can only be performed during the first trimester. If a woman decides to carry the baby to term and give birth, it is necessary to inform relatives about the predicted deviation in the baby’s health.
If the child has a birth defect will require immediate surgical intervention immediately after birth, it is necessary that the birth take place in a specialized specialized clinic, where the child will receive appropriate care.
It is also necessary to immediately decide whether the birth will be carried out naturally, or whether a caesarean section will be necessary.

Important! No study guarantees 100% reliability of testing.

A number of cases have been recorded when, with a positive result of fetal pathology, a woman was delivered from the burden of an absolutely healthy child. True, there were also errors of the opposite kind, but, according to medical statistics, there were much fewer of them. Accuracy rates for chorionic villus sampling approach 99%.

Risks and consequences

Judging by the assessments of women who were diagnosed through chorionic villus sampling, and as noted by their reviews, this procedure is painless, but may cause some discomfort. Especially in the puncture area when conducting the transabdominal testing method.

Invasive chorionic villus testing involves penetration into the uterus with a developing fetus. Therefore, there are certain risks that accompany the collection of biomaterial using any testing method:

The risk of intrauterine infection increases;
There is a short leakage of amniotic fluid;
There is a cramping, but quickly stopping pain in the lower abdomen;
Extremely rarely - violation of the integrity of the amniotic sac.

Did you know? Spontaneous termination of pregnancy after chorionic villus sampling is extremely rare and occurs in one in 440 women, which is 0.4% of those examined.

In what cases is the examination not carried out?

If there is a threat of miscarriage.
The uterus is in a state of hypertonicity
Chronic diseases are getting worse.
In case of bloody discharge from the cervix.
Diagnosed with uterine fibroids.
The presence of adhesions is noted in the small pelvis.
Lack of access to chorionic villi.
When a woman is pregnant with twins.
When the uterus is bent.

Video

From the informational video offered for viewing, you will learn a lot of new and useful information about diagnostics using the method of testing and taking samples for chorionic villus biopsy. A conversation about chromosomal pathology of the fetus, destroying all fears of the procedure, is conducted by obstetrician-gynecologist, doctor of the highest category, Gulnor Myrzabekova.

Actual information

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If you have had a chorionic villus biopsy, please share your impressions. What did you experience at the time of the diagnosis, and how long did it last? Were there any difficulties during the period after the tests, and how did you cope with them? We are waiting for your answers. All comments, reviews and additional information can be left on this page under the article. Take part in discussions, and together we will make our site the most informative.

Chorionic villus sampling (CVS) is a procedure for taking chorionic villi cells for analysis and identifying possible gene and chromosomal abnormalities in them. The chorion is the outer membrane of the fetus, covered with villi, which is closely adjacent to the uterus. Since it is of fruit origin, its cells carry complete information about any anomalies of the unborn child. By then it is completely transformed into the placenta. If for some reason it was impossible to do a CVS in a timely manner, then you can take a small piece of the placenta for examination. Read more about placentocentesis in the corresponding article.

Chorionic villus sampling is performed at 8 to 12 weeks of pregnancy.

Indications for CVS

Indications:

The woman’s age is over 35 years, since the frequency of spontaneous mutations increases with age, even in the absence of other risk factors;
Presence of signs of congenital pathology during ultrasound screening;
Consanguineous marriage;
The presence of a chromosomal rearrangement, hereditary disease or developmental defect in one of the spouses;
Presence of monogenic hereditary diseases in relatives (phenylketonuria, cystic fibrosis, spinal amyotrophy);
The need to determine the sex of the fetus, since some diseases are linked to the X chromosome and appear only in boys (hemophilia A and B, optic nerve atrophy);
The birth of a child with a hereditary disease or developmental defect;
A history of spontaneous miscarriages, stillbirths, primary amenorrhea, primary infertility in spouses;
Adverse effects of environmental factors in the early stages of pregnancy (radioactive radiation, inhalation of vaporous poisons, etc.);
Taking embryotoxic drugs in early pregnancy;
X-ray examination in the early stages.

Contraindications for biopsy

Contraindications:

Inflammatory diseases of the vagina and cervix, or abdominal skin (depending on the puncture site).
A relative contraindication is the presence of HIV infection in a pregnant woman, as the likelihood of transmitting it to the fetus increases. If analysis is necessary, increase the dose of antiretoviral drugs.

Methods for taking chorionic villus sampling

Depending on the method of taking material for research, there are:

Transcervical approach– a thin flexible tube is inserted through the vagina and cervical canal into the uterine cavity and a piece of chorionic villi is carefully pinched off.
Transabdominal method– a puncture is made through the skin of the woman’s abdomen with a thin needle and a few chorion cells are collected into it.

Additionally The choice of method depends on the location of the chorionic villi. Regardless of the method of taking the analysis, the study is carried out under mandatory ultrasound control.

Complications after BVC

Early complications of biopsy:

Spontaneous miscarriage, according to two Russian multicenter studies, with transabdominal biopsy is 0.5 - 1.5%, and with transcervical biopsy it can reach 7.5%.
Intrauterine infection;
Bleeding from the puncture site;
Formation of parietal hematomas, which can provoke detachment of the ovum

Late complications:

Low body weight of the newborn (less than 2500g).

Chorionic villus biopsy, like other invasive methods of diagnosing the fetus, is carried out only with the consent of the pregnant woman. It should be borne in mind that with BVC, abnormalities of the fetal neural tube are not detected, so it is possible that amniocentesis will also have to be performed at 18–22 weeks of pregnancy (read more in the article “”) Before making a decision, it is necessary, if possible, to calmly weigh all the pros and cons and only then refuse to conduct the study. Knowing the child’s illness, it is always easier to prepare for his birth and, if necessary, carry out treatment immediately after birth.

A long-awaited and planned pregnancy does not always go smoothly. Sometimes abnormalities are detected in the baby or doctors have suspicions regarding the development of the fetus based on the results of tests and ultrasound examinations. In order to confirm or refute these fears, a number of diagnostic procedures are performed, one of which is chorionic villus biopsy. This study is carried out in exceptional cases when there is a possibility of developing a genetic or other dangerous disease. Sometimes such a procedure causes complications or the development of infection, so before giving consent, a pregnant woman should carefully weigh the pros and cons, thinking about her health and the life of her unborn baby. When is analysis recommended, how does it happen and what can be revealed with its help?

Indications for chorionic villus sampling

Chorionic villus sampling is a diagnostic procedure that involves taking chorionic villus cells for further examination. This analysis makes it possible to identify the presence of genetic and chromosomal pathologies in the early stages, which allows parents to make a decision about the future fate of the child. The chorion is the outer membrane of the fetus, which carries all the genetic information about it, about the presence of abnormalities and developmental pathologies. With development, the chorion is transformed into the placenta. This happens around 15-16 weeks, so the procedure is carried out before this period (ideally 8-12 weeks).

There are a number of indications for chorionic villus biopsy and the doctor prescribes the procedure in the following cases:

Taking a chorionic villus sample allows you to determine the presence of chromosomal abnormalities (Patau syndrome, and others). In this case, the accuracy of the result will be 95-99%, but it is impossible to determine the severity of the disease using such an analysis. In addition, genetic abnormalities can be identified if there is a suspicion of the development of a specific disease. Chorionic villus biopsy cannot detect defects in the development of the fetal neural tube, so it may have to be additionally performed after the 16th week of pregnancy.

How to prepare for research

The procedure does not require special or thorough preparation. When using transcervical access, it is important to first undergo an examination by a gynecologist and make sure that there is no infection or inflammatory process in the cervix and vagina. In addition, an ultrasound examination of the fetus is performed, which allows you to determine the exact duration of pregnancy. It is imperative to make sure that there are no contraindications and to realistically assess the need for the procedure, taking into account all possible risks and complications after it.

Procedure

There are two types of procedures, depending on the method of removing biological material for analysis:

At the end of the procedure, the doctor checks the baby's heartbeat to assess his condition and make sure there is no damage to the fetus. If there is a risk of Rh conflict, an injection is required after the procedure.
Often the procedure causes a number of complications, about which the doctor is obliged to warn the woman before obtaining consent. Negative consequences may occur immediately after the analysis or several months after it.

Complications after chorionic villus sampling:

Spontaneous miscarriage (occurs rarely - 1-1.5% of cases, but there is a risk).
Infection, which can cause disruption of fetal development.
Bloody discharge from the puncture site.
Premature birth.
Low weight of a newborn – up to 2400 kg.

After the procedure, be sure to devote the rest of the day to rest, limiting physical activity and emotional experiences. The results of the analysis are ready, as a rule, in 7-10 days, and a detailed genetic response after 2-4 weeks.
After receiving the research data, the doctor explains to the woman their significance, voices possible risks and complications in the development of the child. Some couples decide to terminate the pregnancy, while others prefer to keep the baby, raise and love him no matter what.

Contraindications to the procedure

The procedure also has its contraindications, in which it is strictly forbidden to take a chorionic villus sample even if there are strong indications. These factors include:

Chorionic villus biopsy is performed only if there are compelling indications and with the consent of the pregnant woman. It is important to warn the woman about the possible risks and explain the need to perform the study. A timely diagnosis will allow the family to make a decision about the future fate of the baby and prepare mentally for his birth.

Chorion, or villous membrane, appears for the first time in mammals, develops from trophoblast and extraembryonic mesoderm.

There are three periods in the formation of the chorion: previllous, the period of villous formation and the period of cotyledons. A three-week embryo at the gastrula stage.

The amnion cavity and yolk sac are formed. The trophoblast cells that form the placenta come into contact with the blood vessels of the uterus. The embryo is connected to the trophoblast by a body stem derived from the extraembryonic mesoderm. The allantois grows into the pedicle of the body, angiogenesis occurs here, and subsequently the umbilical cord is formed with the umbilical (allantoic) vessels passing through it: two umbilical arteries and one umbilical vein.

* Previllous period. During implantation, trophoblast cells proliferate and form cytotrophoblasts. As it interacts with the endometrium, the trophoblast begins to cytolytically destroy endometrial tissue, resulting in cavities (lacunae) filled with maternal blood. The lacunae are separated by partitions of trophoblast cells; these are the primary villi. After the appearance of lacunae, the blastocyst can be called the amniotic sac.
* Villous period. During this period, primary, secondary and tertiary villi are successively formed.

¦ Primary villi are clusters of cytotrophoblast cells surrounded by syncytiotrophoblast.

¦ Secondary villi. On the 12-13th day, extraembryonic mesoderm grows into the primary villi, which leads to the formation of secondary villi, evenly distributed over the entire surface of the fetal egg. The epithelium of secondary villi is represented by light, round-shaped cells with large nuclei. Above the epithelium there is a syncytium with unclear boundaries, dark granular cytoplasm, a brush border and polymorphic nuclei.

¦ Tertiary villi. From the 3rd week of development, tertiary villi containing blood vessels appear. This period is called placentation. The villi facing the basal part of the decidua are supplied with blood not only from vessels originating from the chorionic mesoderm, but also from the vessels of the allantois.

The period of connection of the branches of the umbilical vessels with the local circulatory network coincides with the beginning of heart contractions (21st day of development), and the circulation of embryonic blood begins in the tertiary villi. Vascularization of the chorionic villi ends at the 10th week of pregnancy. By this time, the placental barrier is formed. Not all chorionic villi are equally well developed. The villi facing the capsular part of the falling membrane are poorly developed and gradually disappear. Therefore, the chorion in this part is called smooth.

* Cotyledon period. The cotyledon, the structural and functional unit of the formed placenta, is formed by the stem villi and its branches containing the fetal vessels. By the 140th day of pregnancy, 10-12 large, 40-50 small and up to 150 rudimentary cotyledons have been formed in the placenta. By the 4th month of pregnancy, the formation of the main structures of the placenta is completed. The lacunae of a fully formed placenta contain about 150 ml of maternal blood, which is completely replaced 3-4 times per minute. The total surface of the villi reaches 14 m2, which ensures a high level of exchange between the pregnant woman and the fetus.

The smooth chorion is located between the aqueous and decidua and consists of four layers: cellular, reticular, pseudobasal membrane and trophoblast.

The cell layer is adjacent to the spongy layer of the amnion. It is well differentiated in the early stages of pregnancy and is almost undetectable in mature membranes. The reticular (or fibrous) layer of the chorion is the most durable.

The trophoblast is indistinctly separated from the adjacent decidua. Its cells penetrate deep into, providing a close connection between the chorionic and decidual membranes, in connection with which some authors [Govorka E. 1970; Wulf K N., 1981] consider these layers as a single choriodecidual complex. The trophoblast consists of several rows of cells having a round or polygonal shape, one or more nuclei. Between the choriotrophoblasts there are tubules, bordered, like the amnion tubules, by microvilli and containing tissue fluid.

Microfibrils, desmosomes, large mitochondria, endoplasmic reticulum and other ultrastructures are well developed in the cytoplasm of trophoblast cells. High functional activity, including pinocytosis, is indicated by the presence of vacuoles. A high content of RNA, glycogen, protein, amino acids, mucoproteins and mucopolysaccharides, as well as phosphorus compounds and many enzymes, including thermostable alkaline phosphatase, was found here. Fibrinoid is deposited in the trophoblast, in which the remains of villi are visible, devoid of epithelium and retaining only fibrous fibrous stroma without vessels.

The functional activity of the smooth chorion remains until the end of pregnancy. There are indications of the synthesis in it of human chorionic gonadotropin, AK.TG, prolactin and prostaglandins, the precursor of which - arachidonic acid - is found in high concentrations in the chorion as part of phospholipids. There are no fetal group antigens in the chorionic membrane.

The physical properties of the fetal membranes differ from each other. The amniotic membrane has a high density and can withstand pressure 5 times greater than the chorion. Rupture of the smooth chorion during childbirth occurs earlier than the amnion. The experiment demonstrated the possibility of regeneration of membranes after their rupture.

Chorionic pathologies

It is also important to carefully study the size and structure of the chorion in the first trimester of pregnancy. Normally, from 8-9 weeks the chorion ceases to be circular, part of it thickens and becomes the site of formation of the fetal part of the placenta. The thickness of the chorion increases with the course of pregnancy, amounting to 7.5 mm at 7 weeks and 13.3 mm at 13 weeks. Pathology of the chorion, detected by echography in the first trimester, is represented by retrochorial hematomas (50%), structural heterogeneity (28%), hypoplasia (22%).

According to many researchers, in the presence of retrochorial hematomas, the probability of spontaneous abortion exceeds 30%; Chorionic hypoplasia in 85-90% of cases precedes fetal death (non-developing pregnancy); The heterogeneity of the chorion structure clearly correlates with intrauterine infection (up to 75%).

Section of the chorion villi of a 17-day-old human embryo (“Crimea”). Microphotograph: 1 - symplastotrophoblast; 2 - cytotrophoblast; 3 - chorion mesenchyme (according to N.P. Barsukov)