Uterine lining


The uterine lining, also called the endometrium, is a pink-colored layer of mucous membrane that lines the inside of the uterus.
The lining of the uterus plays a particularly important role during pregnancy when the fertilized egg cell uses the lining of the uterus for implantation.
In women who have gone through puberty and are still before their menopause, the mucous membrane is subject to hormonal influences.
Sex hormones influence the menstrual cycle and thus the mucous membrane during this time.
If a fertilized egg fails to implant, part of the mucous membrane is shed and menstruation occurs.

Function of the lining of the uterus

In general, the lining of the uterus is a protective inner layer of the uterus in all women of all ages, which protects the organ with mucous membrane cells (Epithelial layer) lines.
After puberty, the mucous membrane is subject to hormonal influence and plays an important role in pregnancy.
Since the uterine lining is necessary for the fertilized egg cell to implant, the hormonally controlled cycle of the mucous membrane is an essential part of the body's preparation for pregnancy.

In the days after the last menstrual period, there is a change in the tissue of the mucous membrane.
Through the production of certain sex hormones, the mucous membrane is stimulated to enlarge, so-called proliferation takes place.
After ovulation, which takes place around the middle of the cycle, the so-called secretion phase of the uterine lining is initiated.
In this process, nutrient-containing fluids are secreted by gland cells in the mucous membrane.
This should create the most perfect conditions possible for the fertilized egg cell to implant.
If pregnancy does not occur, part of the uterine lining is secreted by a hormonal change and a menstrual period occurs.

How does the thickness of the uterine lining change?

The thickness of the uterine lining varies depending on the point in time in the individual cycle.
Since this only occurs after puberty and only lasts until menopause, the thickness of the uterine lining usually only varies in women of sexually mature age.
The thickness of the lining of the uterus can be determined using an ultrasound scan.
This is usually not necessary, but can be carried out as part of the gynecological diagnosis if certain symptoms are present.
In women who are before menopause and after puberty, an endometrium thickness of over 14mm is indicative of a possible pregnancy. In women who are after their menopause, a mucous membrane over 11mm thick can be indicative of the presence of uterine lining cancer, which is why such a finding should be clarified.

Menstruation starts at the beginning of the cycle. With this, a large part of the mucous membrane is shed.
The thickness is therefore reduced in this phase of the cycle.
Menstruation is over after a few days and a phase follows in which the mucous membrane grows and becomes significantly thicker.
This phase of the cycle, which lasts about 9 days, is also called the proliferation or growth phase.
In the secretion phase afterwards, in which the glands in the mucous membrane secrete more fluids, the uterine lining continues to grow.
If pregnancy has not occurred, the end of the cycle is initiated by the beginning of the menstrual period and the repeated shedding of a large part of the mucous membrane.

Structure of the uterine lining

The structure of the uterine lining differs depending on the phase of the cycle.
In general, a distinction can be made between two different layers of the mucous membrane.
The so-called basal layer lies on the uterine muscles.
This is always retained on the muscles during the cycle and does not detach from it during the period.
This means that a layer of mucous membrane always remains on the uterus even during the menstrual period.
The functional layer, which is subject to changes during the cycle, must be distinguished from this.
In the secretion phase, this layer can be subdivided into a so-called “compact” and a “sponge-like” layer.

The mucous membrane consists of different cell types, which take on different functions.
The basic structure of the mucous membrane is made up of so-called epithelial cells.
These represent the basic structure of the uterine lining.
In addition, there are glandular cells, which are increasingly formed, especially in the growth and secretion phase, and produce a liquid secretion.

What happens with my period?

Period, also called menstruation or menstruation, is the regular monthly shedding of part of the lining of the uterus.
Here, only the functional layer of the mucous membrane is shed, while the basal layer remains on the uterine muscles.
The period begins with the maturity of the woman in puberty, the first period also being called Menarche referred to as.
Menopause is the last period.
Meanwhile, your period marks the start of your menstrual cycle.

In addition to the lining of the uterus, the period also contains blood and fluids formed by the glandular cells.
The rejection of the mucous membrane can be accompanied by pain, which, however, is usually not a cause for concern.
The volume of the menstrual period is usually limited to a maximum of 200ml, with the duration of the period usually being between four and six days.

Read more on this topic at: The female cycle

How does the uterine lining change during pregnancy?

The lining of the uterus plays an important role during pregnancy.
After the egg cell has been fertilized, it nests in the layer of the mucous membrane.
In the days before, the growth and secretion phase of the uterine lining took place, which is why it is in an ideal starting position for the egg cell. Certain pregnancy hormones cause the mucous membrane to change into the so-called decidua graviditatis after the egg cell has implanted.
In order to be able to supply the egg cell with sufficient nutrients, there are many blood vessels and glands in the layers of the mucous membrane.
If the egg cell is successfully fertilized, it grows in the mucous membrane, now called the decidua.
Together with the layers of the egg cell, the shell that has now formed around the egg cell is also called the egg cavity.

After the baby is born, the body sheds the uterine lining, which the child used as part of the egg cavity, under hormone control, and the regular menstrual cycle begins again.

Read more on this topic at: fertilization

Uterine lining disorders

Endometrial cancer

The uterine lining cancer (so-called endometrial carcinoma) is one of the most common cancers in women in Germany.
A risk factor for this is an excessively high level of estrogen over several years.
Initially, there is an enlargement of the mucous membrane cells, the so-called hyperplasia.

In addition, a distinction is made between estrogen-dependent (type 1) and estrogen-independent tumors (type 2).
Type 1 tumors make up the largest proportion of endometrial cancer.
The main symptom of endometrial cancer is vaginal bleeding.
There is usually no intial pain.
Women before menopause (premenopausal) often have intermenstrual bleeding (metrorrhagia) or a prolonged menstrual period over 7 days (menorrhagia).

The diagnosis is usually carried out by a vaginal examination with a subsequent transvaginal ultrasound.
If you suspect an uterine lining cancer, a uterine specimen and a scraping of the uterine cavity are then performed.

The therapy always depends on the stage of the cancer and the lymph node involvement.
The therapy of choice, however, is the complete removal of the uterus, fallopian tubes and ovaries with additional removal of the surrounding lymph nodes.
Radiation therapy can then be carried out postoperatively.

You can find out what causes menstrual disorders are based on:
Menstrual Disorders - What You Should Know

Uterine lining inflammation

Inflammation of the womb lining (endometritis) often affects young women.
The cause is usually an infection with the bacteria gonococci or chlamydia.
A distinction is made between two forms of infection: On the one hand, it can be an ascending infection, i.e. the infection spread from “below”, that is mostly from the cervix to “above”.
This is the most common type of endometritis.
Another possibility would be a descending infection, in which the pathogens multiply from the abdominal cavity downwards towards the genital organs.

Endometritis often manifests itself as a side-stressed lower abdominal pressure pain and unspecific symptoms such as fever, nausea and vomiting.
In the worst case, the inflammation can become chronic.

The diagnosis is carried out by an abdominal and a vaginal examination as well as a microbiological culture.
Sonography can also be used.

The uterine lining inflammation is treated with antibiotics.

You can find more information about infection with gonocci, also known as gonorrhea, at:
How to protect yourself from gonorrhea

What happens when the uterine lining is obliterated?

The uterine lining (so-called endometrial ablation) is a gentle surgical measure when the menstruation is too heavy.
There are several procedures that all have in common is the removal of the lining of the uterus.
With the so-called gold mesh catheter endometrial ablation, a gold mesh is inserted into the uterus under anesthesia after a uterine mirror has been performed and the mucous membrane is obliterated by high-frequency current.
The obliteration takes about 2 minutes on average.
As with all operations, obliteration of the uterine lining also involves general operational risks such as damage to neighboring organs, bleeding or recurrences after the operation.

Why can the lining of the uterus be too thin?

A thin lining of the uterus can have many different causes.
It can also be a reason why a fertilized egg cell cannot implant itself in the lining of the uterus and thus the desire to have children does not materialize.
The following is an overview of the causes:

  • low levels of estrogen

  • decreased blood flow to the mucous membrane

  • Infections like endometritis

  • Scarring

  • Condition after operations on the uterus

  • hormonal contraception

  • Clomiphene (promotes ovulation)

There are many therapeutic options available to rebuild the thin lining of the uterus.
If the estrogen level is consistently low, the gynecologist will prescribe a hormone-containing preparation that can be used orally or vaginally.
An iron or vitamin E deficiency can also affect the blood flow.
For this reason, particular care should be taken to ensure adequate intake of these substances if the uterine lining is thin.
Medicinal products that dilate blood vessels can also help if the arteries in the uterine lining are narrowed.

You can find out what causes low estrogen levels at:
Estrogen Deficiency - How Does It Come About?

How does the lining of the uterus change during menopause?

During menopause, the level of estrogen in every woman's body drops because the ovaries no longer produce estrogen.
As a result, the uterine lining is no longer built up and thus becomes smaller (atrophied).
Therefore there is no monthly menstrual period.
Since the mucous membrane becomes smaller and has less blood supply than before the menopause, pregnancy is no longer possible.
Increasing age also has an impact on muscles, connective tissue and ligaments, which is why, among other things, the uterus can sag and sink as these structures recede.

You can read about the signs of menopause in the following article:
You can recognize menopause by these signs

Can you break down the uterine lining without bleeding?

A natural breakdown of the uterine lining without bleeding is not possible.
However, there is an operative variant, the scraping.
The scraping (abrasion) is used either for diagnosis or treatment.
A common use is for bleeding disorders.
Especially in women shortly before or during the menopause, bleeding can occur more frequently if the mucous membrane cannot be shed properly.
Then the lining of the uterus is removed by abrasion.

The cell cycle usually changes after such an intervention.
The menstrual period starts a little delayed because the mucous membrane has to completely recede.