Why did the fertilized egg fail to implant?

The fallopian tube is like a hotel, where sperm and eggs meet and then the fertilized egg is sent to the uterine cavity. However, if the fallopian tube is inflamed, it will narrow the fallopian tube and it will be difficult for the fertilized egg to return to the uterine cavity. In this case, you can't take root in the uterus, but you can only settle in the fallopian tube. But to a certain extent, the fallopian tube will rupture, and the pregnant mother will have abdominal pain and bleeding, and in severe cases, she will be shocked and dizzy.

First, endocrine disorders.

Many pregnant mothers don't pay attention to endocrine disorders. In fact, this problem will not only affect women's menstruation and ovulation, but also affect the implantation of fertilized eggs. Many women's endometrial abnormalities are due to insufficient luteal function and progesterone, which leads to the failure of fertilized eggs to implant.

Second, there is an abortion experience.

Some women don't know how to cherish themselves when they are young, which leads to unexpected pregnancy, but they are unable to raise their children, so they can only have an abortion, while some pregnant mothers have an abortion because of fetal malformation when they are pregnant. Both of these situations have an impact on women's next child, because the endometrium will become thinner, and fertilized eggs are difficult to implant and prone to abortion.

Third, embryo defects.

If a fertilized egg wants to be healthy, then the fertilized egg provided by parents must be healthy. If one of the eggs and sperm is abnormal, problems will occur after the combination, including the possibility of deformity and chromosome abnormality. The third generation of IVF can screen out abnormal fertilized eggs with abnormal chromosomes, which greatly improves the health status of fertilized eggs.

Fourth, the pregnant mother's uterus is abnormal

Some women have uterine deformation, endometrial polyp adhesion, endometrial tuberculosis and so on. Will directly affect the implantation of fertilized eggs. As a space for fetal development, if there is abnormality, the living environment of the fetus will naturally be affected. Even if implanted, there will be many problems in the future, and the probability of premature abortion is very high.

Many times, it's not that there is something wrong with the body, but that the pregnant mother is too nervous. When people are in a state of tension for a long time, it will lead to endocrine disorders, thus inhibiting ovarian function. Sometimes it is possible to ovulate early or not, and pregnant mothers should relax.

First, after the fertilized egg is implanted, the temperature of the pregnant mother will change a little, and this temperature change is very small, so it is difficult for the pregnant mother to feel it.

Second, pregnant mothers stop menstruating, which is also the first feeling that many women find themselves pregnant. If they don't have menstruation after sleeping together, then they should pay attention. They may be pregnant.

Third, lower abdominal pain may occur after implantation, but not all pregnant mothers have this feeling, but this pain is short-lived and mild. Vaginal bleeding is the same, less blood, pink, not all pregnant mothers have it.

If the fertilized egg fails to implant in the uterus, it means ectopic pregnancy. Pregnant mothers will have a B-ultrasound on May 6th to see if the fetus is in the uterus. If not, do surgery in time, otherwise it will do great harm to the pregnant mother.

Under normal circumstances, the egg begins to implant on the 6th-7th day after fertilization, but it was still very small at that time and could not be seen by B-ultrasound. Only about 20-30 days after implantation can we see the small gestational sac by B-ultrasound. The process of implantation of fertilized eggs is silent, and the female body has not changed much. The failure of implantation of fertilized eggs means that they are not pregnant, have normal menstruation, and the implantation of fertilized eggs has failed.

Common reasons are as follows.

1. The embryo itself is defective.

In most cases, the healthiest sperm always combines with the egg, but in some special cases, some abnormal sperm will combine with the egg first, and sometimes it is because after the egg combines with one sperm, the second sperm also combines with the same egg, so the fertilized egg formed in this way is inherently defective and generally not easy to implant.

2. Luteal insufficiency

If the luteal function is insufficient, the progesterone level will be low, and the endometrium can not make corresponding changes for pregnancy under the action of progesterone, thus affecting the implantation of fertilized eggs.

3. Uterine factors

The uterus is called the cradle of life. If the fertilized egg encounters a warm and comfortable uterine environment, it will settle here more happily and healthily. After implantation, the endometrium began to grow and thicken actively, providing more comprehensive services for fertilized eggs. If there are uterine dysplasia, submucosal myoma, endometrial polyps, intrauterine adhesions, endometrial inflammation and other factors will affect the implantation of fertilized eggs.

4. Immune factors

Sperm, seminal plasma or fertilized eggs are antigen substances, which are absorbed by vagina and uterine epithelium and produce antibody substances through immune reaction, so that sperm and eggs cannot be combined or fertilized eggs cannot be implanted.

5. Excessive mental stress

We often see some women who have not been pregnant for a long time. The longer they stay, the more nervous they are, but the less likely they are to get pregnant. In fact, among many factors that cause infertility, mental and psychological factors are also an important reason.

Female reproductive endocrine system is influenced and regulated by cerebral cortex. If they are nervous and anxious for a long time, they will disturb the endocrine system and even inhibit the function of ovaries. During natural pregnancy, ovulation may be advanced, delayed or not, which greatly reduces the chances of conception.

1. Localization: The zona pellucida disappeared before implantation, and the late blastocyst contacted the endometrium with its inner cell mass.

2. Adhesion: After the late blastocyst adheres to the endometrium, the outer layer of the trophoblast is syncytiotrophoblast and the inner layer is cytotrophoblast.

3. Invasion: The syncytial trophoblast secretes proteolytic enzymes, dissolves endometrial cells, stroma and blood vessels, and is completely buried in and covered by endometrium.

The main reasons for the failure of fertilized egg implantation are as follows.

If the chromosome of sperm or egg is abnormal, the embryo itself is defective, and this unhealthy embryo will fail to implant.

When female endocrine disorders, ovarian luteal function is weakened, and progesterone secretion is insufficient, it will cause endometrial abnormalities and lead to implantation failure.

Abnormal uterine development, or endometrial diseases, can also affect implantation.

If you want to get pregnant smoothly, you must pay attention to the pre-pregnancy examination, find out the factors affecting pregnancy in time, and actively treat it.

Getting pregnant is getting harder and harder for some people. The process from sperm-egg combination to embryo development and maturity is very complicated. Among them, whether the embryo can be safely implanted into the endometrium is also very important for pregnancy. Then why do some fertilized eggs fail to implant in the endometrium?

Sperm and egg meet somewhere in the fallopian tube, and after many mitoses, they enter the uterine cavity under the movement of villi in the fallopian tube. The fertilized egg enters the uterus and has to undergo further "inspection". If the "test" is successful, the fertilized egg can be safely implanted into the uterus, and various indicators of pregnancy will appear at this time. In this "test", the examiner is the endometrium, which monitors the trypsin signal to determine whether the embryo can develop further. High-quality embryos will produce a lot of trypsin, which will lead to the increase of short-term active calcium, thus triggering the release of a large number of implantation factors, so that embryos can successfully implant in the mother and communicate with each other. For embryos with developmental retardation, the endometrium will shut them out. Because they cannot produce trypsin correctly, they cannot activate the "calcium switch". After implantation failure, there is no necessary connection between mother and embryo. With the onset of menstruation, the endometrium will fall off and the embryo will be excreted. Successful implantation is not an easy task, which depends not only on the embryo itself, but also on a series of factors such as endometrium.

Women who have undergone various tests but are not pregnant need not worry too much. Because like a clock, adult women will continue to ovulate in the next menstrual cycle, and they can expect sperm and eggs to combine in the next menstrual cycle and successfully implant into the uterus.

Answer: Zhang Ting, Master of Medicine.

Hello, I'm Ma Jing, and I'm glad to answer your question.

Before answering this question, let's talk about what is "fertilized egg implantation" ~

After sexual intercourse, sperm and eggs will combine to form fertilized eggs, then reach the uterus for implantation and development, gradually form a fetus, grow and develop, and finally give birth.

6-7 days after sexual intercourse, the fertilized egg will reach the uterus and start implantation. The "bed" of "implantation" is the uterine wall, mostly in the anterior or posterior wall of the upper part of the uterine body.

Generally speaking, the process of implantation of fertilized eggs is silent and the body will not change much. However, some subtle changes will be felt by sensitive women, such as a slight drop in basal body temperature, implantation bleeding, stomach pain, cold symptoms, fatigue and so on. Of course, these performances will vary from person to person.

A fertilized egg is like a seed, and a uterus is like soil. Whether there is a problem with "seed" or "soil", it will affect the success of fertilized egg implantation.

1, bad seeds: the quality of the embryo itself is not good.

The main cause of poor embryo quality is chromosome abnormality, such as sperm or egg chromosome abnormality; There are also maternal physical diseases (such as hypertension, diabetes, viral infection or bacterial toxins), abnormal maternal hormone secretion, abnormal endometrium, smoking and drinking, which will affect the quality of embryos.

2. Poor soil: uterine problems

3. Luteal insufficiency

Luteal insufficiency, that is, low progesterone, will also affect the implantation of normal fertilized eggs, causing threatened abortion or infertility.

The failure of fertilized egg implantation is mainly manifested in the occurrence of "biochemical pregnancy" It was clearly detected that the fertilized egg was pregnant, but it bled in a few days, and then it was examined by B-ultrasound, and there was no gestational sac at all. This shows that it is biochemical, that the implantation of fertilized eggs has failed, and that pregnancy has failed.

However, biochemical pregnancy, like normal menstruation, does not affect the next pregnancy, and can continue to prepare for pregnancy next month.

Sperm and egg meet miraculously in fallopian tube, form fertilized egg, and life begins. However, the failure of fertilized egg implantation also affects women's conception, so let's understand why fertilized egg implantation fails.

Why does the implantation of fertilized eggs fail?

1, the fertilized egg itself is defective.

Because the fertilized egg itself has defects, it will lead to the failure of fertilized egg implantation.

2. Uterine factors

The failure of fertilized egg implantation is probably due to uterine dysplasia, submucosal myoma, endometrial polyps, intrauterine adhesions, endometrial tuberculosis and so on.

3. Immune factors

The research on immune factors in recent years shows that there are two kinds of immune conditions that affect pregnancy.

Homologous immunity: Sperm, seminal plasma or fertilized eggs are antigen substances, which are absorbed by vagina and uterine epithelium and produce antibody substances through immune reaction, so that sperm and eggs cannot be combined or fertilized eggs cannot be implanted.

Autoimmunity: the serum of women who think they are infertile.

4. Ovarian luteal insufficiency

If a woman's progesterone secretion is insufficient, then her endometrium will be abnormal, which will affect the implantation of fertilized eggs.

There are autoantibodies in zona pellucida, which can prevent sperm from penetrating the egg after reacting with zona pellucida, thus preventing fertilization.

5. Excessive mental stress

Especially there is no serious anxiety and psychological stress caused by pregnancy.

The above is the introduction of the reasons for the failure of fertilized egg implantation. Giving birth to new life is a complex physiological process, which must be the normal combination of sperm and eggs. To understand the reasons for the failure of fertilized eggs implantation and treat them symptomatically in order to achieve rapid pregnancy.

What's it like to implant a fertilized egg?

Many young women who have no pregnancy experience always have such questions when they suspect that they are pregnant: What symptoms will a fertilized egg have when it is implanted? Can I feel it? I want to use this to preliminarily judge whether I am pregnant or not. In fact, the process of fertilized eggs from fertilization to implantation is almost silent, except for a few pregnant women who have physiological implantation bleeding and slight spasm. However, in the next time, you can slowly feel a series of symptoms that make you feel pregnant.

1, feeling queasy. Some people begin to feel sick in the first few weeks after conception. You may feel nauseous or queasy. Although morning sickness is also called morning sickness, the symptoms of nausea are not limited to the morning. You may feel queasy all day and all night.

2. The breasts become softer. If your breasts feel tingling, soft and swollen, you may be pregnant. This symptom may appear in the first few days after conception. If you suddenly don't recognize your breasts, you may be pregnant. Don't worry! When your body adapts to a lot of hormones, the pain will subside and your breasts will no longer feel uncomfortable.

I feel tired. A lot of lutein (a hormone) will make you feel exhausted. Almost all pregnant women have this symptom. You can observe other symptoms to confirm your suspicion.

4. Go to the toilet often. After the fertilized egg is implanted into the uterine wall, it begins to secrete chorionic gonadotropin (hCG). This will stimulate you to urinate frequently, so you will go to the toilet more often than before.

5, bleeding or spasm. On the eighth day after ovulation and implantation, you may have slight pink or brown spots, and convulsions may also accompany this situation. During the physiological period, there may be some punctate bleeding, but this is not the real physiological period. This is the result of implantation of fertilized eggs in endometrium.

1, the fertilized egg itself is defective.

Because the fertilized egg itself has defects, it will lead to the failure of fertilized egg implantation.

2. Uterine factors

The failure of fertilized egg implantation is probably due to uterine dysplasia, submucosal myoma, endometrial polyps, intrauterine adhesions, endometrial tuberculosis and so on.

3. Immune factors

The research on immune factors in recent years shows that there are two kinds of immune conditions that affect pregnancy.

Homologous immunity: Sperm, seminal plasma or fertilized eggs are antigen substances, which are absorbed by vagina and uterine epithelium and produce antibody substances through immune reaction, so that sperm and eggs cannot be combined or fertilized eggs cannot be implanted.

Autoimmunity: the serum of women who think they are infertile.

4. Ovarian luteal insufficiency

If a woman's progesterone secretion is insufficient, then her endometrium will be abnormal, which will affect the implantation of fertilized eggs.

There are autoantibodies in zona pellucida, which can prevent sperm from penetrating the egg after reacting with zona pellucida, thus preventing fertilization.

5. Excessive mental stress

Especially there is no serious anxiety and psychological stress caused by pregnancy.

The above is the introduction of the reasons for the failure of fertilized egg implantation. Giving birth to new life is a complex physiological process, which must be the normal combination of sperm and eggs. To understand the reasons for the failure of fertilized eggs implantation and treat them symptomatically in order to achieve rapid pregnancy.

The fertilized egg is formed in the fallopian tube and transported to the uterine cavity through the movement of the fallopian tube. However, infectious diseases in pelvic cavity are all diseases of reproductive organs. Inflammatory changes will occur in fallopian tubes, which will be immobile or blocked, leading to infertility and ectopic pregnancy. However, the fertilized egg cannot be implanted when it is transported to the uterine cavity, which is a pathological change of endometrial infection, and the specific disease is endometritis. Endometritis can not only lead to implantation failure of fertilized eggs, but also cause various fertility diseases, such as ectopic pregnancy, hydatidiform mole, abortion, placenta previa and so on. Therefore, preventing the occurrence of gynecological inflammatory diseases can avoid the occurrence of various reproductive diseases and gynecological diseases. The way to prevent gynecological inflammation is to conform to the physiology of tubal movement and help discharge the substances in the pelvic cavity. After having sex, women always keep the oviduct moving well and the sexual physiological cycle running normally. It will ensure that the female genitalia is always in a healthy state.

What is the cause of repeated implant failure?

Repeated implantation failure is a hot topic in the field of reproduction at present, and its etiology is complex, which may be related to many factors such as decreased endometrial receptivity, embryo quality, autoimmune and so on. Any factors that affect implantation may lead to implantation failure. This article will discuss the influence of uterine organic lesions on repeated implantation failure, in order to provide basis for clinical treatment of repeated implantation failure.

Repeated implantation failure (RIF) is a difficult point in in vitro fertilization-embryo transfer (IVF-ET). At present, there is no uniform standard for the definition of repeated implantation failure. Tan et al. proposed that repeated implantation failure means that after 2-6 IVF-ET cycles (including freeze-thaw embryo transfer cycles), * * * transplanted more than 10 high-quality embryos, but still failed to get pregnant. Simon and others believe that repeated implantation failure refers to high-quality embryo transfer for ≥3 cycles (including frozen-thawed embryo transfer cycle), but pregnancy has not yet been obtained.

Conditions for implantation of fertilized eggs

The implantation conditions of fertilized eggs include disappearance of zona pellucida, differentiation of blastocyst trophoblast into syncytial trophoblast, synchronous development of blastocyst and endometrium, coordinated function, and adequate progesterone secretion of pregnant women. The "implantation window" for uterus to receive embryos is very short, so repeated implantation failure is related to many factors such as endometrial receptivity, embryo quality, autoimmunity and so on. However, the organic lesion of uterus is one of the reasons that affect endometrial receptivity.

First, uterine malformation

Primitive uterus:

Also known as the trace uterus, it is because the bilateral accessory kidneys stop developing soon after they meet. The uterus is very small, there is no uterine cavity, only a small substantive uterus can be seen. Color Doppler ultrasound suggests that there is no endometrium and there is no possibility of pregnancy.

Naive uterus:

The accessory kidney stopped developing in a short time after confluence, and the uterus was smaller than normal, with the length, width and thickness less than 5 cm, 4 cm and 2 cm respectively. Due to uterine dysplasia, the volume of uterine cavity is small and the endometrium is slender. Endometrial volume

Double uterus:

It is because the bilateral accessory mesonephros did not fuse at all, and developed into two uterine bodies and two cervix respectively. Chan et al. think that the double uterus may not be closely related to infertility through systematic review and analysis. If the development of two uterine cavities is similar to that of normal uterine cavities, it has little effect on implantation.

Biangular uterus:

Because of incomplete fusion of the bottom of the uterus, the uterine cavity of the horn uterus is narrow, and implantation failure may occur, which may be related to uterine cavity stenosis and decreased blood supply to the endometrium.

Saddle uterus:

Also known as the arched uterus, it is saddle-shaped because the bottom of the uterus sinks slightly when it is fused. However, because the shape of the saddle-shaped uterine cavity is close to the normal uterus, it generally does not affect embryo implantation.

Mediastinal uterus

It is due to the incomplete fusion of the accessory middle renal ducts on both sides, which forms a diaphragm in the uterine cavity. The uterine cavity is completely divided into two parts from the bottom of the uterus to the cervix, which is a complete mediastinum; Partial separation is incomplete mediastinum. The mediastinal uterus causes many implantation failures for the following reasons:

(1) The main tissue components of mediastinum are fibrous tissue and muscle tissue, and the number of endometrial glands in mediastinum is less than that in normal uterus, which leads to the decrease of estrogen and progesterone receptors and the decrease of endometrial receptivity.

(2) The blood vessels of mediastinal mucosa are radial, and the blood supply is worse than that of normal uterine cavity, which leads to the failure of implantation. Clinically, for patients with infertility caused by uterine mediastinum, selective hysterectomy is often performed. Hysterectomy can not only remove the site unsuitable for implantation, but also improve endometrial function, endometrial receptivity and pregnancy rate by promoting vascular regeneration of tissues connected with the fundus of uterus.

Uniangular uterus:

This is due to the development of one accessory mesonephros and the undeveloped accessory mesonephros on the other side. Due to the lack of another corner of the uterus, the uterine cavity of unicorned uterus is often smaller than that of normal uterus, and the uterine fibers are unevenly distributed, which is prone to uncoordinated uterine contraction, which may be related to repeated implantation failure.

Secondly, hysteromyoma, adenomyosis and endometriosis.

Uterine fibroids:

According to the relationship between myoma and muscle wall, it can be divided into intramural myoma, subserous myoma and submucosal myoma. Subserous myoma often has little effect on embryo implantation, but pressing or approaching intramural myoma and submucosal myoma will reduce endometrial receptivity and lead to implantation failure. Studies have shown that uterine fibroids that deform the uterine cavity can reduce the embryo implantation rate and pregnancy rate of patients with assisted reproductive technology, regardless of the size of fibroids. However, Christopoulos and others believe that multiple myomas (more than 2) and larger intramural myomas (>: 3 cm) will reduce the success rate of IVF even if they do not affect the uterine cavity.

The reasons for the decrease of endometrial receptivity caused by hysteromyoma may be as follows:

(1) Myoma can cause abnormal contraction of uterine smooth muscle, especially during ovulation and luteal phase. Compared with normal women, endometrial peristalsis wave increases, leading to implantation failure and infertility.

(2) The compression of uterine cavity by myoma changes the volume and structure of uterine cavity, affects the implantation site and interferes with implantation.

(3) Myoma may cause compression of nearby veins, leading to congestion and dilatation of endometrial venous plexus, even causing intimal ischemia and increased release of local vasoactive substances, affecting the blood supply of embryos, which is not conducive to embryo implantation.

(4) Myoma increases the area of uterine cavity, the secretion of endometrial glands increases, and pelvic congestion increases leucorrhea. Once submucosal myoma is infected, a large number of purulent leucorrhea can appear, which is not conducive to embryo implantation.

(5) Interleukin-10(IL- 10), glycoprotein and other related implantation factors decreased, and the down-regulation of HOXA 10 gene resulted in decidualization defects, which may be related to repeated implantation failures.

(6) The local imbalance of vascular growth factor, chemokine and tumor necrosis factor in hysteromyoma affects embryo adhesion and implantation. Therefore, for patients with repeated implantation failure due to uterine fibroids, it is suggested that fibroids should be treated first, and then embryo transfer should be carried out in order to obtain a good outcome.

Adenomyosis and endometriosis;

(1) adenomyosis: The uterus is uniform and spherical, which makes the uterine cavity bigger and the endometrial area bigger, which affects the uterine contraction and makes implantation difficult. At the same time, its muscle wall is obviously thickened and hardened, and the fibrous tissue around the focus is proliferated due to repeated local ectopic endometrial bleeding, and there is no obvious boundary with the surrounding muscle layer. Because there are fibrous bands and microcapsule cavities in the muscular layer, the uterine contraction is poor, which affects implantation. Secondly, the lack of submucosa in the basal layer of endometrium in adenomyosis leads to the loss of endometrial tissue structure, which affects the blood supply of endometrium and thus interferes with implantation. Finally, some studies have found that the expression of progesterone receptor in adenomyosis tissue is down-regulated, and embryo implantation needs the support of progesterone, so patients with adenomyosis are prone to repeated implantation failures.

(2) Endometriosis: The infertility rate of patients with endometriosis is as high as 40%. Holoch and other studies believe that endometriosis may affect fertilization and embryo implantation by interfering with oocyte maturation and inhibiting myometrial contraction, and then lead to infertility. It has been found that the expression of integrin αvβ3 in endometrium of about 50% patients with endometriosis is decreased, and even not expressed in some cases. The expression of integrin is consistent with the "implantation window" of endometrium, especially the expression of αvβ3, which can be used as a molecular marker of endometrial receptivity.

In addition, the expression of placental protein A, an important symbol of embryo implantation in patients with endometriosis, decreased, suggesting that it may lead to the decrease of endometrial receptivity. The expression of other implantation biomarkers, such as leukemia inhibitory factor, osteopontin and lysophosphatidic acid receptor -3, also decreased in patients with endometriosis, and the expression of adhesion molecules decreased in patients with endometriosis, which may interfere with the process of embryo implantation adhesion. Endometriosis is similar to adenomyosis, which shows that the expression of estrogen receptor in endometrium increases and the activity of progesterone decreases, which leads to the increase of estrogen level and progesterone resistance, which has an adverse effect on endometrial receptivity and embryo implantation, leading to implantation failure.

Third, uterine cavity lesions

Endometritis:

Cicinelli et al. pointed out that the incidence of chronic endometritis was 57.54% among women who failed to implant repeatedly, indicating that endometritis is closely related to repeated implantation failure. Endometritis is mostly caused by the upward spread of vulvovaginal infection, and the pathogens are bacteria, viruses, prokaryotic microorganisms and protozoa. Inflammatory stimulation and pathological changes can lead to changes in endometrial structure, and related pathogens can stimulate the immune response of the body, and a large number of sensitized active cells are activated to produce a variety of cytokines. These inflammatory cells are embryotoxic. In addition, hyperemia of endometrium, infiltration of interstitial inflammatory cells, exudation of inflammatory mediators of fibrous connective tissue and capillaries are not conducive to embryo implantation.

Wu et al. found that prolactin and insulin-like growth factor binding protein 1(IGFBP- 1) were down-regulated in patients with chronic endometritis, both of which were signs of decidualization. They believe that patients with chronic endometritis affect the decidualization of endometrial stromal cells by interfering with sex hormone receptors. Pinta and others believe that endometrial peristalsis changes in patients with endometritis during ovulation and luteal phase, and the endometrium contracts abnormally, which is not conducive to implantation. Cicinelli et al. compared the pregnancy outcome of endometritis patients treated with antibiotics and untreated endometritis patients treated with IVF, and the results showed that antibiotic treatment could significantly improve the pregnancy rate and pregnancy outcome. Therefore, for patients with endometritis, it is recommended to carry out embryo transfer after anti-inflammatory treatment.

Endometrial polyps:

Endometrial polyp is a localized hyperplasia of the basal layer of endometrium, whose pedicle protrudes into the uterine cavity and consists of stroma, thick-walled blood vessels and endometrial glands composed of a small amount of dense fibrous connective tissue. Endometrial polyps, especially multiple polyps and larger polyps, can form space occupation and mechanical interference in the uterine cavity, leading to changes in the shape and volume of the uterine cavity and affecting the blood supply of the endometrium; Moreover, most endometrial polyps are inflammatory polyps, and there are many factors such as inflammatory stimulation reactions that lead to repeated implantation failures. A meta-analysis shows that hysteroscopic endometrial polypectomy can significantly improve the pregnancy rate.

Intrauterine adhesion:

Also known as Aschemann syndrome, it refers to the phenomenon of partial or total adhesion of uterine cavity after endometrial injury, more than 90% of which is caused by curettage. Intima injury will lead to the changes of intimal blood vessels, and the high resistance of uterine spiral arterioles, the changes of microvessel density and vascular endothelial growth factor can all affect intimal regeneration. After intrauterine adhesion, the uterine cavity shrinks, and normal endometrial tissue is replaced by fibrous tissue, which leads to endometrial tissue fibrosis and repeated implantation failure.

Endometrial hyperplasia (EH):

According to the standards of the International Association of Gynecological Pathology, EH can be divided into three categories:

(1) Simple hyperplasia: also known as adenocystic type. Microscopically, the number of glands increased, the glandular cavities were cystic, with different sizes and interstitial hyperplasia. The glands are separate.

(2) Complex hyperplasia: also known as adenoma, the glands are obviously proliferated, crowded and complicated in structure, and the glands are adjacent to each other back to back. Due to gland hyperplasia, stroma decreased.

(3) Atypical hyperplasia: Gland hyperplasia with atypical cell hyperplasia is precancerous lesion.

EH is mostly related to the continuous stimulation of estrogen, and there is no progesterone antagonism. Valbuena et al. found that high levels of estradiol affect embryo adhesion. At the same time, estrogen can stimulate the proliferative growth of endometrial glands and stroma. When the endogenous or exogenous progesterone level decreases, the endometrium cannot be transformed into secretory phase, which leads to implantation failure.

Fourth, uterine malignant tumor.

Endometrial cancer:

The high risk factors of endometrial cancer in young women include anovulatory dysfunctional uterine bleeding, infertility, polycystic ovary syndrome and hereditary nonpolyposis colorectal cancer syndrome. The mechanism of endometrial cancer may be related to estrogen stimulation, insulin resistance and progesterone receptor (PGR) gene polymorphism without long-term progesterone resistance. There is no progesterone antagonism in endometrium for a long time, which leads to the failure of endometrial secretion transformation. At the same time, there are cancer cells occupying space in the uterine cavity, which interferes with implantation and leads to repeated implantation failures. For patients with early endometrial cancer, high-dose progesterone can be used for conservative treatment, so that endometrial pathology can be completely relieved, and IVF treatment can improve their pregnancy rate.

Cervical cancer:

Cervical cancer occupies the first place in female reproductive organ tumors, and its "rejuvenation" trend is increasingly obvious. For early young patients with fertility requirements, cervical conization or cervical resection is feasible. However, surgery destroys the integrity of the patient's cervix. The regeneration and repair of cervical tissue is an inflammatory infiltration process, which destroys the cervical immune microenvironment and cytokine environment in the early pregnancy, increases the chances of patients' upward infection, and may lead to endometrial inflammation and implantation failure.

To sum up, the failure of repeated implantation caused by organic uterine diseases is mainly due to the influence on uterine cavity structure and blood supply of endometrium, and the regulation of implantation-related factors such as estrogen and progesterone receptors in endometrium, which leads to the decrease of endometrial receptivity. For uterine lesions with clear etiology, such as uterine fibroids, endometrial polyps, intrauterine adhesions, etc. Surgical treatment can be performed before transplantation; For the lesions that repeatedly fail to implant due to endometrial microenvironment and related regulatory factors, it is suggested to treat them individually and improve endometrial receptivity before embryo transfer, so as to improve the implantation rate and pregnancy rate.