The endometrium, or endometrium, is the tissue that lines the inside of a woman's uterus. Its structure and functions change periodically in the subsequent phases of the menstrual cycle. It is the endometrium that constitutes the layer of the uterine wall that systematically exfoliates during menstrual bleeding. Proper functioning of the endometrium is necessary for the implantation of the embryo after fertilization and its proper development along with the course of pregnancy. Find out how the endometrium is built, how it works and what diseases can develop in it.

Endometriumis the endometrium. Its thickness varies not only with the individual phases of the menstrual cycle, but also with the age of the woman.

Structure of the endometrium

The uterine wall consists of three basic layers:

  • of the peritoneum, covering the entire organ from the outside
  • muscular, the thickest of the layers, which enables uterine contractions
  • mucous, located innermost (also known as the endometrium)

The endometrium, like other mucous membranes, is made up of epithelial cells, connective tissue, as well as blood vessels, nerves and cells of the immune system. A very important element of its structure are glands that produce secretions. The functioning of the endometrium is related to its division into two layers: basic and functional.

The basal layer of the endometriumlies deep and its structure is constant and does not change during the menstrual cycle.

The functional layer of the endometriumundergoes cyclical reconstruction - alternating growth and exfoliation. The role of these changes is to prepare the uterus for embryo implantation. The reconstruction of the functional layer after menstruation is possible on the basis of the constantly present "base", i.e. the basal layer.

Endometrial cycle

The endometrium is very sensitive to the action of female sex hormones: estrogens and progesterone. Changes in their concentration in the body during the monthly cycle result in the reconstruction of the endometrium.

Periodic changes in the structure of the endometrium are called the endometrial cycle. The next phases of this cycle are:

  • proliferation (or multiplication) phase
  • secret (i.e., secretion) phase
  • phase of menstruation (i.e. exfoliation)

From the 5th day after the end of menstruation, the ovaries begin to intensively produce estrogen. Through them, systematic reconstruction of the functional layer of the endometrium, which was exfoliated during the preceding menstruation, takes place.

About the 14th day of the cycle, ovulation takes place, which means that an egg is released from the follicle. This bubble then turns into a so-called The corpus luteum, which produces another very important hormone - progesterone.

The task of progesterone is to prepare the uterine mucosa for implantation of the embryo. Thanks to it, the endometrium becomes thick and well supplied with blood. The glands expand and the remaining cells store nutrients.

If fertilization is not achieved, the vessels that carry blood to the endometrium contract. The ischemic mucosa dies and peels off as menstrual bleeding. The entire endometrial cycle then begins anew.

Endometrium during pregnancy

If the egg is fertilized during the monthly cycle, the properly prepared endometrium becomes the implantation site of the embryo. The uterine mucosa undergoes further transformation and is now called temporal.

Temporal, and more specifically one of its layers (so-called temporal basal), is the maternal part of the placenta. Its proper functioning is ensured by the constant flow of blood and nutrients, which enables the development of the fetus. The temporal body also has important immune functions - thanks to the different functioning of immune cells within it, the mother's body does not recognize the fetus as a foreign one and thus prevents rejection of the pregnancy.

Another role of the temporal is its influence on the hormonal balance - on the one hand, it is strongly influenced by hormones produced during pregnancy, and on the other hand, it has the ability to release hormone and signaling molecules into the bloodstream.

Endometrial tests

There are several methods available for examining the condition of the endometrium. The choice of the test method depends on the medical indications: the patient's he alth condition, perceived ailments and diseases suspected by the doctor. The most frequently used tests in the diagnosis of endometrial diseases include:

  • ultrasound examination (USG)

Ultrasonography is a non-invasive examination. Its primary use is to measure the thickness of the endometrium. It is usually done in the so-called Transvaginal ultrasound. The thickness of the mucosauterus changes with the course of the menstrual cycle.

The thinnest endometrium is visible in the test performed right after the end of menstruation - its thickness should then not exceed 5 mm. In subsequent phases of the cycle, the endometrium systematically thickens. In the perovulatory period it may reach 7-10 mm. We observe the greatest thickness of the endometrium just before menstruation - usually it is 10 to 15 mm. After the menopause, the endometrium should not exceed 5 mm in thickness.

Ultrasound is especially useful to rule out disease processes - if the thickness of the endometrium does not exceed alarming values, no further diagnostics is usually needed. On the other hand, if the examining physician finds abnormal thickening of the endometrium, the presence of additional lesions (e.g. polyps) or other pathologies, they will usually refer the patient for additional tests.

  • endometrial biopsy

Endometrial biopsy involves taking a fragment of the endometrium with the use of special specula and then analyzing the obtained fragment in a microscopic examination. Indications for an endometrial biopsy include menstrual disorders, infertility, vaginal bleeding (including postmenopausal bleeding), as well as suspicion of a neoplastic process.

A more invasive method of obtaining endometrial fragments for microscopic examination is curettage of the uterine cavity. This surgery is usually performed under general anesthesia. The doctor widens the cervical canal with special tools, and then scrapes the uterine mucosa and sends it for microscopic examination. The endometrium after such treatment is fully regenerated within five days.

Curettage is a procedure with a higher risk of complications, but on the other hand, it allows obtaining a large amount of material for examination. Thanks to this, there is a greater chance of downloading those fragments in which the disease process is taking place.

  • hysteroscopy

Hysteroscopy is a surgical procedure in which a small camera is inserted inside the uterus, which allows you to see the inside of the uterine cavity from the inside. During hysteroscopy, it is possible to see the endometrium in detail, as well as to visualize its possible pathologies: polyps, adhesions and hyperplastic changes.

Hysteroscopy may be combined with the collection of material for a biopsy. This combination has a very significant advantage - the fragments of the endometrium are not taken "blindly", but specifically from those places that arouse any suspicions by doctors. In addition to diagnostic applications, simultaneous treatment is also possible during hysteroscopysurgical - for example removal of polyps.

Endometrial diseases

The improper functioning of the endometrium and the disease processes taking place in it may manifest itself in the form of menstrual disorders, abnormal bleeding, problems with becoming pregnant, and pain. The most common endometrial diseases include:

  • endometritis

Endometritis is most often associated with gynecological operations: cesarean section, curettage of the uterine cavity or hysteroscopy. Endometrial infection can also occur in the postpartum period. Typical symptoms of such inflammation are abdominal pain, fever and vaginal bleeding.

Inflammation can, in addition to the endometrium, also affect the fallopian tubes and ovaries, and other surrounding organs. The most common factor causing endometritis are bacteria, which is why the most effective treatment method is usually appropriately selected antibiotic therapy.

  • endometrial adhesions

Adhesions are scars within the uterine cavity. They can complicate surgical procedures, as well as inflammation or childbirth. Their presence can cause problems with getting pregnant and keeping it.

The most severe type of diseases related to the occurrence of adhesions is the so-called Asherman syndrome. It consists in complete atresia of the uterine cavity as a result of generalized scarring. The first symptom is usually no periods or the presence of very scanty bleeding. This condition is most often the result of too radical curettage of the uterus. Surgery is required to treat all types of adhesions; they are usually removed with a special knife or laser.

  • endometrial polyps

Endometrial polyps are pedunculated structures formed from an overgrown endometrium. The vast majority of these lesions are benign, although all polyps after their removal are subjected to microscopic examination - in rare cases, neoplastic foci are found within them. The size of polyps usually does not exceed a few centimeters. Polyps may not cause any clinical symptoms. However, they often manifest as abnormal bleeding.

The cause of their formation has not been thoroughly known - among other things, the influence of hormonal factors is suspected, although it still has not been fully confirmed in scientific studies. Polyps are most often detected in ultrasound, as well as in other procedures that allow the visualization of the endometrium (e.g. hysteroscopy). Treatment of polypsconsists in their operative removal. In some cases, hormone therapy is used, and sometimes such changes are only left to be observed.

  • endometrial hyperplasia

In endometrial hyperplasia, glandular cells can grow and multiply excessively. The endometrium then becomes overgrown and thickened. The main reason for this is that estrogen stimulates the endometrium too much and is not balanced by the action of progesterone. The risk factors for such disorders include

  • obesity
  • use of estrogen-containing drugs (e.g. in hormone replacement therapy)
  • other diseases causing an increase in estrogen concentration

Abnormal endometrial thickness is considered to be>5 mm in postmenopausal women (>8 mm in women using hormone replacement therapy). Merely thickening the endometrium is not sufficient to assess the disease process. A very important element of diagnostics is microscopic examination of a fragment of the endometrium, obtained, for example, during a biopsy. In the microscopic (histopathological) examination we can obtain two types of results: hyperplasia without atypia or atypical hyperplasia.

In hyperplasia without atypia, the endometrium is thickened, but the cells are normal. This type of growth is associated with a very low risk of developing cancer. Its treatment most often involves the use of hormone therapy (drugs based on progesterone and its derivatives). Sometimes treatment is abandoned because such changes may resolve on their own.

Atypical endometrial hyperplasiais a much more serious condition. It carries the risk of developing into endometrial cancer. For this reason, the detection of atypical endometrial hyperplasia is an indication for prophylactic uterine removal. If this type of hyperplasia is diagnosed in a patient who wishes to become pregnant in the future, hormone therapy is usually introduced and careful monitoring is carried out for early diagnosis of a possible cancer.

  • endometrial cancer

Endometrial cancer is the second most common malignant neoplasm of the female reproductive system (the most common cancer in this group is cervical cancer). Most cases are diagnosed in the sixth and seventh decade of life (between the ages of 50 and 70).

Increased risk of developing this neoplasm concerns patients with hormonal disorders (predominance of estrogen activity). The greatest probability of this type of disorder is in obese women in the perimenopausal period.

During this time, the ovaries reduce the production of sex hormones (the concentration of progesterone decreases), while adipose tissue actively converts other hormones into estrogens. Maintaining a he althy body weight, proper diet and exercise are therefore one of the ways to reduce the risk of developing endometrial cancer.

Other risk factors include:

  • taking medications containing estrogens
  • diabetes
  • no offspring

Endometrial cancer may cause symptoms in the form of abnormal uterine bleeding at an early stage of development. The sooner a cancer is detected, the greater the chance of a successful cure. The most important method of therapy is surgery. Complementary treatments include radio- and chemotherapy, as well as hormone therapy (progesterone derivatives).

The prognosis, as in the case of other malignant neoplasms, depends on the stage of the disease at the time of diagnosis. If the treatment is started early enough, there is a good chance that the tumor will be completely resected and the patient will fully recover. On the other hand, if the neoplastic process extends beyond the endometrium to the surrounding tissues and lymph nodes, the prognosis worsens.

  • endometriosis

In endometriosis, the lining of the womb occurs where it normally shouldn't be. The most common locations are near the uterus: fallopian tubes, ovaries or surrounding tissues. Less commonly, it is possible to have endometrial tissue in the vagina, bladder or large intestine, and in extreme cases even in the lungs or brain.

An abnormally positioned endometrium is influenced by hormones just like the normal endometrium. Endometriosis can typically cause very painful periods, infertility, and pain during sexual intercourse. However, it often remains completely asymptomatic.

There are several theories explaining the possible mechanisms of the disease, but the specific cause is still unknown.

The disease is chronic and has a tendency to relapse. Depending on the stage and age of the patient, hormonal preparations or surgical removal of endometriosis foci are used among the methods of therapy. The goal of hormonal treatment is to inhibit the stimulating effect of estrogens on the endometrium. In the therapy process, it is also very important to limit the particularly persistent effects of the disease, for example, to treat pain in the event of severe ailments.

  • endometrial atrophy

Atrophythe endometrium is a condition in which the lining of the womb becomes thin as a result of the loss of cells in the womb. Atrophic endometrium is most often the result of a failure to stimulate it by estrogens. This situation can be quite physiological, for example in postmenopausal women. In women of reproductive age, the atrophic endometrium may not be able to accept the egg, leading to secondary infertility.

The diagnosis of endometrial atrophy requires in-depth diagnosis of hormonal disorders that may be the cause of this condition. Of course, a detailed interview is also very important, allowing to determine whether the underlying disease is not, for example, taking medications that inhibit the effect of estrogens.

About the authorKrzysztof BialaziteA medical student at Collegium Medicum in Krakow, slowly entering the world of constant challenges of the doctor's work. She is particularly interested in gynecology and obstetrics, paediatrics and lifestyle medicine. A lover of foreign languages, travel and mountain hiking.

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Category:

Female diseases