The female body is periodically rebuilt (natural cyclical changes) due to the influence of hormones that control complex mechanisms relating to its reproductive system (the set of organs that ensure the process of fertilization). For the onset of pregnancy, a prerequisite must be met - the growth and normal development of ovarian follicles, which act as a kind of "container" for already fertilized eggs.
Interpretation of the concept of "follicle"
This is a small anatomical formation that looks like a gland or a sac filled with intracavitary secretions. The ovarian follicles are located in their cortical layer. They are the main reservoirs for the gradually maturing egg.
Initially, follicles in quantitative terms reach significant values in both ovaries (200 - 500 million), each of which, in turn, contains one germ cell. However, for the entire time of puberty of a woman (30-35 years)only 400-500 specimens reach full maturity.
Internal processes of follicle evolution
They flow in their sacs and are characterized by the multiplication of granulosa or granular cells that fill the entire cavity.
Then, the granular cells produce a fluid that pushes and pushes them apart, while directing them towards the peripheral parts of the follicle (the process of filling the internal cavity with follicular fluid).
As for the follicle itself, it significantly increases both in size and volume (up to a diameter of 15-50 mm). And in terms of content, it is already a liquid with s alts, proteins and other substances.
Outside, it is covered with a connective tissue sheath. And it is precisely this state of the follicle that is considered mature, and it is called the Graaffian vesicle (in honor of the Dutch anatomist and physiologist Renier de Graaf, who discovered this structural component of the ovary in 1672). A mature "bubble" interferes with the maturation of its counterparts.
How big should the follicle be?
With the onset of puberty (14-15 years), he completely completes his development. It is considered normal if during the follicular phase, when the menstrual cycle begins, several follicles mature in both ovaries, of which only one reaches a significant size, which is why it is recognized as dominant. The remaining specimens undergo atresia (reverse development). The product of their vital activity is estrogen, a female sex hormone that affects fertilization, childbirth, as well as calcium content and metabolism.
The dominant follicle, which increases in size by an average of 2-3 mm every day, reaches its normal diameter (18-24 mm) at the time of ovulation.
Generative function as priority
From the inside, the mature follicle is lined with stratified epithelium, it is in it (in the thickened area - the egg-bearing tubercle) that there is a mature egg capable of fertilization. As mentioned above, the normal size of the follicle is 18-24 mm. At the very beginning of the menstrual cycle, its protrusion (resembling a tubercle) is observed on the surface of the ovary.
Further, the walls of the follicle become significantly thinner, which leads to its rupture. So, in place of the Graaffian vesicle, a corpus luteum appears - an important endocrine gland.
Due to a number of hormonal disorders, this gap may be absent, and therefore the egg does not leave the ovary and the ovulation process does not occur. It is this moment that can become the main cause of infertility and dysfunctional bleeding of the uterus.
Folliculometry: definition, possibilities
This is an ultrasound diagnostic study, through which tracking the development and growth of follicles is available. Most often, women resort to it, suffering from infertility or menstrual irregularities. The manipulation in question allows you to track the dynamics of ovulation through ultrasound.
At the beginning of the menstrual cycleit becomes possible to observe the process of growth of the endometrium, and in a later period - the evolution of the follicle. So, you can determine the exact size of the follicles by day of the cycle.
When is folliculometry required?
This diagnostic test allows you to:
- set the onset of ovulation accurate to specific days;
- determine the size of the follicle before ovulation;
- analyze the performance of the follicular apparatus;
- plan the gender of the baby;
- set the integrity of the phases of the menstruation cycle;
- calculate the best day to conceive;
- monitor the progress of multiple pregnancies;
- diagnose menstrual disorders;
- assess the individual hormonal background of the patient;
- monitor the progress of the appropriate treatment.
The value of indicators of the norm and pathology of follicle development
At the very beginning of its evolution, the indicator in the status of "norm" is the size of the follicle in diameter of 15 mm. Further, as mentioned earlier, it increases by 2-3 mm per day.
Many women are interested in the question: "What is the size of the follicle at ovulation?" It is considered normal - about 18-24 mm. Then the corpus luteum appears. At the same time, the level of progesterone in the blood is necessarily increased.
Single ultrasound lacks the ability to build a complete picturedevelopment (maturation) of the follicle, since it is especially important to control each individual stage.
The main pathologies that disrupt the maturation of follicles are:
1. Atresia is the involution of an unovulated follicle. To be precise, after formation, it develops up to a certain point, and then freezes and regresses, thus ovulation never occurs.
2. Persistence - the preservation of the virus, when it is still functionally active, in the cells of tissue cultures or the body over the period characteristic of an acute infection. In this case, the follicle is formed and develops, but its rupture does not occur, as a result of which the luteinizing hormone does not increase. This form of anatomical formation is preserved until the very end of the cycle.
3. A follicular cyst is a type of functional formation localized in the ovarian tissue. In this situation, the unovulated follicle does not rupture, it continues to exist, and fluid most often accumulates in it, and subsequently a cyst larger than 25 mm is formed.
4. Luteinization is the formation of a corpus luteum, which sometimes forms without rupture of the follicle, which subsequently also develops. This situation is possible if there was an earlier increase in the LH value or damage to the structure of the ovary.
Follicle sizes by day of cycle
From the very first days of the next cycle, with the help of ultrasound, it can be seen that there are several antral anatomical formations in the ovaries, which will subsequently grow. Their increase is due to the influencespecial hormones, the main ones being follicle-stimulating hormone (FGS) and estradiol. Provided that their level corresponds to the established norm for the content of these substances in the blood, a woman most often has stable ovulation, and anovulatory cycles are observed no more than twice a year.
Antral follicles in the ovaries, the size of which is insignificant, should be present, according to the norm, in both gonads in an amount not exceeding nine pieces. As a rule, they are no more than 8-9 mm in diameter. Subsequently, it is the antral follicles, under the influence of the corresponding hormones, that will give rise to such an important anatomical formation as the dominant follicle, the size of which in diameter exceeds them by 2.5 times.
The average menstrual cycle is 30 days. Somewhere by the tenth day, the dominant one is outlined from the entire set of antral follicles.
Often, patients have the question: “What size should the follicle be at this stage?” At the first session of folliculometry, it practically does not differ in size from the rest (12-13 mm). It is worth recalling that this diagnostic ultrasound allows you to determine the size of the follicles by day of the cycle.
Also, at the first appointment, the specialist will be able to tell exactly how many dominant follicles have already formed. Most often it is the only one (in the right or left ovary). However, in the case when the patient undergoes a course of special ovulation stimulation, there may be such follicles.several, resulting in a multiple pregnancy, of course, subject to the maturation of two or more dominant anatomical structures.
The second session is held after three days. In his course, the doctor:
- confirms the presence of a dominant follicle;
- determines the size of the follicle by cycles of menstruation;
- fixes (if this is the case) the reverse development of the follicle.
The specialist carefully examines both ovaries of a woman. If you track the size of the follicles by day of the cycle, then at the second session it is 17-18 mm in diameter. It's been around day 13 already.
At the third session (transvaginal ultrasound), you can see that the size of the follicle before ovulation (the peak of its size) took on a value equal to 22-25 mm. This indicates an imminent (in the next few hours) rupture, as a result of which a mature egg will pass into the abdominal cavity, and then penetrate into the fallopian tube. For about a day, she is susceptible to fertilization, and subsequently dies. It should be noted that the viability of the egg is several times less than that of spermatozoa.
There are also cases when the dominant follicle grows at a different rate, which is why more than three sessions of this ultrasound may be required. If the patient has repeatedly recorded his regression, then, as a rule, the doctor prescribes her daily folliculometry (from the 9th-10th day of the cycle). This will allow you to identify the beginning of the regression, and then establish the cause of this phenomenon.
So, it is worth recalling once again that it is possible to determine the size of the follicle by cycles inthe time of the diagnostic ultrasound examination - folliculometry. It will allow not only to control the maturation of the dominant anatomical formation under consideration, but also to identify the causes of deviations that hinder this reproductive process (if any).
Ovulation Stimulation
In another way, her induction. This is a complex of various kinds of medical manipulations, the purpose of which is the onset of pregnancy. It is in demand within the framework of modern gynecology in relation to female infertility due to many reasons.
To begin with, it is worth interpreting the concept of infertility - a condition when a woman under the age of 35 cannot become pregnant for 12 months, subject to an active sexual life, as well as a couple (a woman over 35, and a man - 40), whose pregnancy does not occur for more than six months.
Indications and contraindications for stimulation
Induction is carried out in two cases:
- anovulatory infertility;
- infertility of unknown origin.
The main contraindications for this procedure are:
- violations of the patency of the fallopian tubes;
- impossibility of full diagnostics through ultrasound;
- male infertility;
- depletion of existing follicular reserve.
Ovulation induction is not carried out with long-term treatment of infertility problems (more than two years).
Schemes of the procedure
They are expressed in two protocols:
- increasing minimum doses;
- lowering high doses.
In the first case, during this manipulation, the drug "Clomiphene" (non-steroidal synthetic estrogen), which blocks estradiol receptors, is first introduced. Then the drug is canceled, and thus the feedback mechanism is triggered: an increase in the synthesis of gonadotropic releasing hormones and an active release of luteinizing and follicle-stimulating hormones. Ultimately, this should lead to the maturation of the follicles. So, we can say that Clomiphene is an ovulation indicator.
During this manipulation, regarding the induction of ovulation, only one follicle matures, that is, the likelihood of both multiple pregnancy and related complications (for example, ovarian hyperstimulation syndrome) is practically excluded.
After the moment when the size of the follicles during stimulation according to the first scheme reaches 18 mm in diameter (with an endometrial thickness of 8 mm), triggers are introduced (drugs that mimic the release of LH). Then, after the introduction of hCG, ovulation occurs approximately two days later.
The second scheme of manipulation is applicable mainly to women who have a low ovarian reserve and a low likelihood of an effect from small doses of FSH.
Required indications for this manipulation:
- female age over 35;
- FSH value above 12IU/L (on day 2-3 of the cycle);
- ovarian volume up to 8 cc see;
- secondary amenorrhea and oligomenorrhea;
- presence of ovarian surgery, chemotherapy or radiotherapy.
Visible resultshould appear by the sixth day. A significant side effect affecting the ovaries with this method of ovulation induction is the risk of ovarian hyperstimulation syndrome. In the case when, during the next ultrasound, follicles in the ovaries are detected, the size of which exceeds 10 mm in diameter, the doctor regards this as a signal for preventive procedures for this syndrome.
Control ultrasound
It is needed to confirm ovulation by transvaginal ultrasound. This is as important as the monitoring itself. It was previously mentioned what size the follicle is before ovulation (18-24 mm in diameter), however, even when the required size is reached, the capsule may not break through, and the mature egg will not be released into the abdominal cavity. A control ultrasound is performed 2-3 days after the estimated moment of ovulation.
At this session, the doctor will check the condition of the ovaries for signs of ovulation:
- no dominant follicle;
- the corpus luteum is present;
- there is some fluid in the space behind the uterus.
It is important to note that if the specialist conducts a follow-up ultrasound at a later period, he will no longer detect either fluid or corpus luteum.
Finally, it would be useful to once again answer the question: "What is the size of the follicle during ovulation?" This dominant anatomical formation at the time of ovulation matures to a size of approximately 18 - 24 mm in diameter. It is worth remembering that the size of the endometrium and follicles change depending on the day of the menstrual cycle.
