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Pathology of the uterus as a reason for habitual miscarriage

 
, medical expert
Last reviewed: 19.10.2021
 
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In most women with a violation of the reproductive function, developmental defects of the uterus are combined with hormonal disorders with the formation of an inferior luteal phase of the cycle. Perhaps this is due to the effect on the gonads of the same damaging factor that led to anomalies in the development of the uterus. The mechanism of abortion in the development of the uterus is associated with impaired implantation of the fetal egg, insufficient development of the endometrium, due to insufficient vascularization of the organ, close spatial relationships, functional characteristics of the myometrium.

Malformations of the uterus

A major role in the etiology of habitual miscarriage is played by malformations of the uterus, especially in the termination of pregnancy of the second and third trimesters. The incidence of malformations of the uterus in the population is only 0.5-0.6%. Among women with habitual miscarriage, the incidence of abnormalities in the uterus is between 10 and 15%, according to different authors.

The incidence of uterine malformations among patients examined in the clinics of the Center due to habitual miscarriage is 10.8-14.3% in different years. The reasons for the violation of the reproductive function are seen by most researchers in the anatomical and physiological inferiority of the uterus, concomitant with it of ischemic-cervical insufficiency and the inferior luteal phase of the cycle.

The origin of various malformations of the uterus depends on the stage of embryogenesis in which the teratogenic factor had an effect or hereditary characteristics were realized. The germs of the genital organs occur in man approximately at the end of the 1 st month of embryonic development. Paramezonephalic (Mullerian) ducts, from which the uterus, uterine tubes and the proximal part of the vagina are formed, is laid simultaneously on both sides of the mesoderm on the 4-6th week of intrauterine development. Gradually paramezonephalic ducts approach each other, their middle sections are arranged obliquely and their distal sections merge into an unpaired channel. From the merged parts of these ducts, the uterus and the proximal part of the vagina are formed, and out of the swallowed - mother tubes. Under the influence of unfavorable factors during embryogenesis, the fusion of the ducts is disrupted, resulting in various uterine anomalies. The reasons for the adverse effect on the formation of the genital organs are different: hyperthermia, infections, ionizing radiation, complications of pregnancy, we can not exclude the hereditary cause of the formation of malformations of the uterus. In the literature, the action of the diethylstilbestrol preparation in utero, taken by the mother to preserve the pregnancy, is indicated. This drug causes malformations of the uterus: T-form the uterus, thin convoluted tubes, the absence of vaginal arches, etc. The severity of the development of the abnormality of the uterus depends on the dose and duration of the drug used. Other causes of developmental malformations are not known exactly.

Malformation of the female genitalia is often combined with the developmental defects of the urinary system (for example, with the unicorn uterus on the side of the absent horn, there is often no kidney), tk. These systems are characterized by the generality of ontogeny. When miscarriage occurs most often the following types of abnormalities of the uterus, intrauterine partitions (often incomplete, rarely complete), bicorneous, saddle-shaped, unicorn, double uterus. More severe forms of malformations of the uterus (rudimentary, two-horned with a rudimentary horn) are very rare. For these forms of anomalies, infertility is more common than miscarriage.

The following classification of the developmental defects of the uterus is suggested, which are observed in women with miscarriage.

  • I type - agenesis or hypoplasia;
  • II type - the unicorn uterus;
  • III type - double uterus;
  • IV type - bicornylum;
  • V type - intrauterine partition;
  • VI type-after intrauterine action of diethylstilbestrol.

And points out that with the intrauterine partition often pregnancy is lost in the I trimester because of failure of placentation, and the remaining developmental deficiencies most often lead to termination of pregnancy in the II and III trimesters.

Genital infantilism

Often, termination of pregnancy can be due to uterine hypoplasia due to genital infantilism, which is a particular manifestation of a complex pathological process. It is characterized by underdevelopment of the genital organs and various disorders in the hypothalamus-pituitary-ovarian-uterus system.

The pathogenesis of the development of genital infantilism is complex and not fully understood. With sexual infantilism associated a large number of complications (violations of the menstrual cycle, sexual life and childbearing function). According to most researchers, the underdevelopment of the sexual apparatus is caused by the inadequacy of sex hormones. In 53% of women with uterine hypoplasia, menstrual irregularities are observed, and when tested by functional diagnostic tests, ovarian hypofunction is determined.

The infantile womb is formed during childhood and can be caused by the transferred inflammatory diseases in childhood, in pre- and post-pubertal periods, by disorders of nervous and endocrine regulation of the uterus and by changes in local tissue metabolism. When studying the reproductive function and peculiarities of the course of pregnancy in women with genital infantilism, it was found that in patients with miscarriage, as a rule, normal anthropometric data and well-expressed secondary sexual characteristics are noted. In all women, the infantile womb (hypoplastic uterus, long cervix) is identified, which is confirmed by clinical data, hysterosalngography methods and ultrasound data.

According to the research, in the examination of the functional diagnostics tests of women with genital infantilism during 3-4 menstrual cycles, all women showed a two-phase menstrual cycle with an incomplete luteal phase. With hormonal examination, the level of hormones corresponded to the fluctuations characteristic of the normal menstrual cycle.

The discrepancy between the level of hormones in the blood plasma and tests of functional diagnostics made it possible to assume the presence of an inadequate tissue response to the hormones produced by the ovaries. The determination of levels of reception in the endometrium made it possible to confirm this assumption. The decrease in the content of estradiol in the cytosol and nuclei of cells, the number of cytoplasmic and nuclear receptors, and therefore the hypofunction of the ovaries was clinically determined.

However, with this nosological form, it is more correct to speak not of ovarian hypofunction, but of the inadequacy or inferiority of the endometrium. In the mechanism of abortion in genital infantilism, the leading factor is the uterine factor: inadequate preparation of the endometrium for implantation due to insufficiency of the endometrial receptor, increased excitability of the infantile uterine myometrium, close spatial relationships.

The threat of termination of pregnancy is observed at all stages of pregnancy in women with genital infantilism, as well as in women with malformations of the uterus. In the second trimester of pregnancy, the most frequent complication is ismiko-cervical insufficiency. In later terms, there is a slight excitability of the uterus, an increase in tone, and placental insufficiency often develops. Against the background of genital infantilism and malformations of the uterus, adverse effects of other factors of spontaneous miscarriage are often manifested.

Isthmiko-cervical insufficiency and miscarriage of pregnancy

In the structure of miscarriage in the second trimester of pregnancy, the share of istrmico-cervical insufficiency accounts for 40%, and in III trimester of pregnancy, ischemic-cervical insufficiency occurs in every third case of premature birth. Insufficiency of the cervix is caused by structural and functional changes in the uterine ischemia, the size of which depends on the cyclic changes in the woman's body. Thus, in the two-phase menstrual cycle, in the 1-st phase there is an increase in the tone of the uterine musculature and, accordingly, an expansion of the isthmic department, and in the 2nd phase - a decrease in the tone of the uterus and a narrowing of the isthmic division.

There are organic and functional ischemic-cervical insufficiency. Organic, or post-traumatic, or secondary, ischemic-cervical insufficiency occurs as a result of previous curettage of the uterine cavity, accompanied by a preliminary mechanical extension of the cervical canal, as well as pathological births, incl. With the use of small obstetrical operations, which led to deep ruptures of the cervix.

The pathogenesis of functional isthmico-cervical insufficiency has not been studied enough. A certain role in its development is played by the stimulation of alpha-and inhibition of beta-adrenergic receptors. The sensitivity of alpha receptors is enhanced by hyperestrogenia, and beta receptors - with an increase in the concentration of progesterone. Activation of alpha receptors leads to a reduction in the cervix and an expansion of the isthmus, the reverse situation occurs with the activation of beta receptors. Functional ischemic-cervical insufficiency, thus, occurs with endocrine disorders. With hyperandrogenism, functional ischemic-cervical insufficiency occurs in every third patient. In addition, functional ischemic-cervical insufficiency can occur as a result of a disbalance in the proportion of muscle tissue, the content of which increases to 50% (at a rate of 15%), leading to an early softening of the neck and connective tissue, as well as a change in the reaction of the structural elements of the cervix on neurohumoral stimuli.

Very often there is congenital Isthmiko-cervical insufficiency in women with genital infantilism and malformations of the uterus.

Diagnosis of ischemic-cervical insufficiency is based on clinical-anamnestic, instrumental and laboratory data. With the free introduction into the cervical canal of the expander Geghar No. 6, the secretory phase of the menstrual cycle is diagnosed with ischemic-cervical insufficiency. One of the widely used diagnostic methods is radiological, which is performed on the 18-20 day cycle. In women with ismiko-cervical insufficiency, the mean width of the isthmus is equal to 6.09 mm at a rate of 2.63 mm. It should be noted that the formulation of an accurate diagnosis of ischemic-cervical insufficiency, in the opinion of a number of authors, is possible only during pregnancy, since there are objective conditions for a functional assessment of the cervical and uterine parts of the uterus.

The mechanism of termination of pregnancy for istrmico-cervical insufficiency, regardless of its nature, is that in connection with the shortening and softening of the cervix, the gaping internal pharynx and cervical canal, the fetal egg has no support in the lower segment of the uterus. When the intrauterine pressure rises as the pregnancy develops, the membranes are protruded into the enlarged cervical canal, infected and opened. In the pathogenesis of premature termination of pregnancy in ischemic-cervical insufficiency, an important role is assigned to infectious pathology. In this case, the mechanism of abortion is the same for both organic and functional isthmic-cervical insufficiency.

Infection of the inferior pole of the bladder by the upward pathway can become a "producing" cause of premature termination of pregnancy: metabolites of the inflammatory process exert a cytotoxic effect on the trophoblast, cause an abruption of the chorion (placenta), and in the second half of pregnancy affect the pathogenetic mechanisms that increase the excitability of the uterus, leading to unleashing labor activity and premature interruption. It can be said that, with ischemic-cervical insufficiency, favorable conditions for an ascending infection are created, as a result of which the potential threat of intrauterine infection in pregnant women suffering from cervical insufficiency is high enough.

Myoma of the uterus

Many women with uterine myoma have a normal reproductive function, pregnancy and childbirth without complications. Nevertheless, many researchers note that the threat of interruption is noted in 30-75% of patients with uterine myoma. According to research, 15% of women uterine fibroids caused interruption of pregnancy.

Interruption of pregnancy in women with uterine myoma can be if the size of the uterus and the location of the nodes are unfavorable for the course of pregnancy. Especially unfavorable conditions for the development of pregnancy are created with intermuscular and submucosal localization of the nodes. Submucous myoma most often complicates the course of pregnancy in the first trimester. Large intermuscular fibroids can deform the uterine cavity and create unfavorable conditions for its continuation. Of great importance is the location of the nodes of myoma and the localization of the placenta in relation to the nodes of the tumor. The most unfavorable is such a variant, when placentation occurs in the region of the lower segment and on the myomatous nodes.

No less important in the genesis of miscarriage are hormonal disorders in patients with uterine myoma. Thus, some researchers believe that uterine fibroids are accompanied by absolute or relative progesterone insufficiency, which may be one of the contributing factors of spontaneous abortion.

Premature termination of pregnancy can be caused by high bioelectrical activity of the myometrium and increased enzymatic activity of the uterine contractile complex.

Often, the threat of termination of pregnancy is caused by malnutrition of myoma nodes, the development of edema, or necrosis of the node. In pregnancy, myomatous nodes can undergo changes. Many researchers note that with pregnancy associated with an increase in the tumor, the myoma is softened, becoming more mobile. Others believe that the tumor becomes larger due to increased vascularization of the uterus, expansion of the blood and lymph vessels leading to stagnation of lymph and blood.

When deciding on the preservation of pregnancy in patients with uterine myoma, an individual approach is necessary. It is necessary to take into account the age, prescription of the disease, data on heredity, the presence of concomitant extragenital pathology.

Myoma of the uterus is often combined with endometriosis. According to research, this combination is observed in 80-85% of patients with uterine myoma. Endometriosis has an adverse effect on the course and outcome of pregnancy, spontaneous abortions and premature births are often observed. In other studies, there was no relationship between the frequency of spontaneous interruption and the presence of endometriosis, and the treatment of endometriosis, reducing the incidence of infertility, does not reduce the incidence of miscarriage. Nevertheless, according to our data, the presence of endometriosis, even after hormonal and / or surgical treatment, complicates the course of pregnancy whether in patients with infertility in history or with habitual miscarriage. Apparently, the features of hormonal changes, presumably the autoimmune nature of this pathology lead to a complicated course of pregnancy at all its stages.

Intrauterine synechiae

Intrauterine synechia formed after instrumental interventions or transferred endometritis is diagnosed radiologically in 13.2% of those surveyed for the habitual miscarriage of women in our clinic.

Clinical manifestations of the syndrome of intrauterine synechia depend on the degree of lesion of the endometrium by adhesions, on their location and on the duration of the disease. After the occurrence of intrauterine synechia, only 18.3% of patients retain a two-phase menstrual cycle, most women have an incomplete luteal phase of varying severity, which is typical for patients with habitual miscarriage.

It should be noted that in violation of the basal layer of the endometrium and the appearance of scars, it is almost impossible to restore it, so when large synechia can develop persistent infertility.

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