The female body is periodically rebuilt (natural cyclic changes) due to the action of hormones that control complex mechanisms related to its reproductive system (a set of organs that provide the process of fertilization). For pregnancy to occur, 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 sac filled with intracavitary secretion. Ovarian follicles are in their cortical layer. They are the main reservoirs for the gradually ripening egg.
Initially, the follicles in quantitative measurement reach significant values in both ovaries (200 - 500 million), each of which, in turn, contains one reproductive cell. However, for all the time of puberty women (30-35 years old) reach full maturity only 400-500 copies.
Internal processes of follicular evolution
They flow in their sacs and are characterized by the multiplication of granular or granular cells that fill the entire cavity.
Then the granular cells produce fluid, pushing them apart and spreading them, 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 in volume (up to a diameter of 15-50 mm). And in content - it is already a liquid with salts, proteins and other substances.
Outside, it is covered with a connective tissue membrane. And it is precisely such a state of the follicle that is considered to be mature, and it is called a graaff bubble (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 their colleagues.
What size should the follicle be?
With the onset of puberty (14-15 years), he completely completes his development. It is considered normal if during the period of 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 life is estrogen - a female sex hormone that affects fertilization, childbirth, as well as calcium and metabolism.
The dominant follicle, whose dimensions increase on average by 2-3 mm every day, at the time of ovulation reaches its normal diameter (18-24 mm).
Generative function as a priority
On the inside, the mature follicle is lined with stratified epithelium, and it is in it (in the thickened area, the egg-bearing tubercle) that the mature egg is capable of fertilization. As mentioned above, the normal follicle size is 18-24 mm. At the very beginning of the menstrual cycle, its protrusion (resembling a tubercle) on the surface of the ovary is observed.
Further, the walls of the follicle are significantly thinned, which leads to its rupture. So, a yellow body appears at the place of the graaf bubble - an important gland of internal secretion.
Due to a number of hormonal disorders, this gap may be absent, and therefore the egg does not exit the ovary and the ovulation process does not occur. This moment can become the main cause of infertility and dysfunctional uterine bleeding.
Folliculometry: definition, possibilities
This is an ultrasound diagnostic study by which monitoring of the development and growth of follicles is available. Most often, women who suffer from infertility or menstrual irregularities resort to it. The considered manipulation allows using ultrasound to track the dynamics of ovulation.
At the beginning of the menstrual cycle, it becomes possible to monitor the process of endometrial growth, and in a later period, the evolution of the follicle. So, you can determine the exact size of the follicles by the days of the cycle.
When is folliculometry required?
This diagnostic study allows you to:
- establish 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 child;
- establish the integrity of the phases of the menstruation cycle;
- calculate the optimal day for conceiving a child;
- monitor the course of multiple pregnancy;
- diagnose menstrual irregularities;
- evaluate the individual hormonal background of the patient;
- monitor the progress of the appropriate treatment.
The value of the norm and pathology of the development of the follicle
At the very beginning of its evolution, the indicator in the “norm” status 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 during ovulation?" Normally it is considered - about 18-24 mm. Then a yellow body appears. In this case, the level of progesterone is necessarily increased in the blood.
A single ultrasound is deprived of the ability to build a full-fledged picture of the development (maturation) of the follicle, since it is especially important to monitor each individual stage.
The main pathologies that disrupt follicular maturation are:
1. Atresia - involution of a neovulating follicle. To be precise, after education, it develops to a certain point, and then freezes and regresses, thereby ovulation does not occur.
2. Persistence - the preservation of the virus, when it is still functionally active, in the cells of tissue or body cultures beyond the period characteristic of 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 remains until the very end of the cycle.
3. Follicular cyst - a type of functional formation localized in the tissue of the ovary. In this situation, the neovulated follicle does not rupture, it continues to exist, and most often fluid accumulates in it, and subsequently a cyst larger than 25 mm is formed.
4. Luteinization - the formation of the corpus luteum, which sometimes forms without rupture of the follicle, which subsequently also develops. This situation is possible if there has been a previous increase in the value of LH or damage to the structure of the ovary.
Follicle sizes by day of the cycle
From the very first days of the next cycle with the help of ultrasound, you can notice that in the ovaries there are several antral anatomical structures under consideration, which will subsequently grow. Their increase is due to the influence of special hormones, the dominant among which are follicle-stimulating hormone (FGS) and estradiol. Provided that if their level corresponds to the established norm of the content of these substances in the blood, a woman most often has stable ovulation, and anovulatory cycles are observed no more than two times a year.
Antral follicles in the ovaries, the size of which is insignificant, should be present, according to the testimony of the norm, in both sex glands in an amount not exceeding nine pieces. As a rule, in diameter they are no more than 8-9 mm. 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, whose dimensions in diameter exceed them 2.5 times.
The average menstrual cycle is 30 days. Somewhere by the tenth day, the dominant is outlined from the entire set of antral follicles.
Often patients ask themselves: “What size should the follicle be at this stage?” At the first folliculometry session, it practically does not differ in size from the rest (12-13 mm). It is worth recalling that this diagnostic ultrasound examination allows you to determine the size of the follicles by day of the cycle.
Also at the first appointment, a specialist will be able to accurately say 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 stimulation of ovulation, there may be several such follicles, resulting in a multiple pregnancy, of course, provided that two or more dominant anatomical formations mature.
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 according to the cycles of menstruation;
- fixes (if this takes place) the reverse development of the follicle.
The specialist carefully examines both the ovaries of a woman. If you track the size of the follicles by the days of the cycle, then in the second session in diameter it is 17-18 mm. This is about 13 days.
At the third session (transvaginal ultrasound), you can see that the size of the follicle before ovulation (peak of its size) took a value equal to 22-25 mm. This indicates the imminent (in the next few hours) its rupture, as a result of which a mature egg will pass into the abdominal cavity, and then penetrate 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 sperm.
There are also cases when the dominant follicle grows at a different rate, due to which more than three sessions of this ultrasound may be required. If the patient has repeatedly recorded its regression, then, as a rule, the doctor prescribes her daily folliculometry (from 9-10 days of the cycle). This will reveal 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 a follicle by cycles during a diagnostic ultrasound examination - folliculometry. It will allow not only to control the course of maturation of the dominant considered anatomical formation, but also to identify the causes of deviations that inhibit this reproductive process (if any).
Ovulation stimulation
In another way, its induction. This is a complex of various kinds of medical manipulations, the purpose of which is the onset of pregnancy. It is in demand in 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 where a woman under the age of 35 cannot become pregnant for 12 months, subject to active sexual life, as well as couples (a woman older than 35 and a man 40) in whom pregnancy does not occur whiter 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 patency of the fallopian tubes;
- the inability to conduct a full diagnosis through ultrasound;
- male infertility;
- depletion of existing follicular reserve.
Ovulation is not stimulated with long-term treatment of infertility problems (more than two years).
Schemes of the procedure
They are expressed by two protocols:
- increasing minimum doses;
- lowering high doses.
In the first case, with this manipulation, the drug “Clomiphene” (non-steroidal synthetic estrogen) is first introduced, which blocks estradiol receptors. Then the drug is canceled, and thereby trigger the mechanism of the inverse relationship: increasing the synthesis of gonadotropic releasing hormones and the active release of luteinizing and follicle-stimulating hormones. In the end result, this should lead to the maturation of follicles. So, we can say that the tool "Clomiphene" is an indicator of ovulation.
During this manipulation with regards to the induction of ovulation, only one follicle ripens, that is, the probability of multiple pregnancy and associated complications (for example, ovarian hyperstimulation syndrome) is practically eliminated .
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 (drugs that simulate the release of LH) are introduced. Then, after the introduction of hCG, ovulation occurs in about two days.
The second scheme of manipulation is applicable mainly to women who have a low ovarian reserve and a low probability of the effect of small doses of FSH.
Mandatory indications for this manipulation:
- female age over 35 years;
- FSH value over 12ME / L (on the 2nd-3rd day of the cycle);
- ovarian volume up to 8 cubic meters. cm;
- secondary amenorrhea and oligomenorrhea;
- the presence of ovarian surgery, chemotherapy or radiotherapy.
A visible result should appear by the sixth day. A significant side effect that affects the ovaries with this method of ovulation induction is the risk of their hyperstimulation syndrome. In the case when follicles in the ovaries, the size of which exceeds 10 mm in diameter, are detected during the next ultrasound, the doctor considers this as a signal for carrying out preventive procedures for this syndrome.
Control ultrasound examination
It is necessary to confirm ovulation by transvaginal ultrasound. This is as important as the monitoring itself. It has already been 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, and the mature egg will not enter the abdominal cavity. The control ultrasound is carried out 2-3 days after the alleged moment of ovulation.
At this session, the doctor will check the condition of the ovaries for signs of completed ovulation:
- there is no dominant follicle;
- there is a yellow body;
- there is a little fluid in the space behind the uterus.
It is important to note that if a specialist conducts a follow-up ultrasound in a later period, he will not detect any fluid or corpus luteum.
Finally, it will 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 sizes equal to approximately 18 - 24 mm in diameter. It is worth remembering that the sizes of the endometrium and follicles vary depending on the day of the menstrual cycle.