Many women do not even know about the existence of the corpus luteum, and therefore are very surprised when a doctor detects it on an ultrasound scan and even measures its diameter. The corpus luteum is an endocrine gland that appears and disappears every month, contributing to the regularity of the female cycle and the woman's ability to bear a child.
What it is?
All women of different ages, races, height have one thing in common - they have the same menstrual cycle, the phases of which are sequential. After menstruation, the maturation of follicles begins, one of which will become dominant. In it, as in a cozy bag, the egg matures, in the middle of the cycle the follicle ruptures, ovulation occurs. The egg leaves its "refuge" and enters the abdominal cavity, and from there into the fallopian tube, where it can be fertilized within a day or a half.
In place of the follicle, a temporary formation is formed from the remnants of its membrane - gland that produces progesterone. Due to the color of the pigment inside it, she received the name of the corpus luteum.... It is difficult to overestimate its importance for a woman, because this education allows the female body to prepare for a possible pregnancy. Of course, the gland cannot "know" whether the egg is fertilized or not, but the production of progesterone occurs anyway. This hormone helps prepare the endometrium for possible implantation. While the ovum moves into the uterus within a week after ovulation, the endometrium becomes looser to make it easier for the embryo to implant.
Also, progesterone lowers a woman's immunity so that immune cells do not kill the embryo, mistaking it for a foreign body, since the baby's genetic makeup is only half akin to a woman.
Also, under the influence of progesterone in the early stages of pregnancy, the mother's body accumulates nutrients and fat. The hormone relaxes the muscles of the uterus, preventing it from straining, which contributes to the bearing of the fetus.
The corpus luteum cannot exist for a long time if there was no conception... If the embryo is not implanted, after 10-12 days it dies and dissolves, the production of progesterone in large quantities stops. In a woman's body, estrogen begins to control everything and menstruation begins. Before menstruation, the corpus luteum ceases to be such and is transformed into a whitish body that does not have a functional load, and then disappears altogether.
After conception and successful implantation, the chorionic villi begin to produce the more understandable and familiar to many hormone hCG (this is why pregnancy tests become "striped"). Chorionic gonadotropin does not allow the corpus luteum to cease to exist, so the gland continues to function until the end of the first trimester of pregnancy. Then the placenta is formed, the functions of the "factory" of progesterone fall on it. The corpus luteum regresses as unnecessary after 11-13 weeks of pregnancy.
Localization
The corpus luteum cannot be located either in the uterus, as some women think, or in the fallopian tubes, or anywhere else outside the ovaries. It always strictly develops exclusively on the ovary, from which ovulation occurred... The woman has two ovaries. Follicles grow on both at the very beginning of a new cycle, but the dominant one is usually one, the rest undergo reverse development. The dominant follicle is located either on the right or on the left ovary. The corpus luteum also occupies the place that previously belonged to the follicle vesicle.
Sometimes a woman develops two yellow bodies at once. What this means is easy to understand - ovulation was double, two dominant follicles burst at once, so there are high chances that a woman can become pregnant with twins or even triplets. The very phenomenon of double ovulation is not very common, the body saves the follicular reserve, since a woman does not replenish or renew it, and the number of eggs is given to her once for a lifetime.
When the reserve is exhausted, the climax will begin. After double ovulation, temporary glands can develop on one ovary, and on different ones - it depends on where the bursting follicles were located.
What does ultrasound show?
An ordinary layman who knows little about the intricacies of ultrasound diagnostics will hardly understand anything on the scanner screen if the doctor does not accompany the examination with a detailed description. The corpus luteum is visualized in the ovarian region and looks like a small sac, anechoic formation... Echogenicity is absent, since there is a certain amount of liquid medium inside the temporary gland. The gland is formed immediately after ovulation, but it is possible to see it on ultrasound only 3-4 days after it, since the size of the corpus luteum at the initial stage of formation is very insignificant.
Ultrasound is performed in two ways - transabdominal and intravaginal, the second of which is considered more reliable and informative.
Having determined the presence of a temporary gland in the right or left ovary, the doctor measures its diameter. This indicator is important in order to understand how the corpus luteum corresponds to the stage of its development. But to assess the performance of the gland, the thickness of the endometrium is measured (we remember that progesterone acts on it in the first place).
Among all the glands of the female body, it is this one that is best supplied with blood, and at the stage of vascularization, the blood flow in it is the fastest. So the corpus luteum saturates the woman's blood with progesterone. And ultrasound with a Doppler allows you to establish the exact characteristics of the blood flow velocity, which also indicates a full or defective gland.
In simple terms, the ultrasound shows the following:
in which ovary was the maturation of the egg;
whether ovulation occurred in this cycle;
whether the corpus luteum does its job well enough.
If the corpus luteum is not detected, is absent, then the doctor states that there was no ovulation in this cycle. There is no need to worry - anovulatory cycles occur in perfectly healthy women normally up to 2 times a year at the age of 20 to 35 years. But women of older ages may have more such cycles - up to 5-6 per year. Therefore, older women may find it more difficult to conceive a child even with normal health. If, for several cycles in a row, the absence of a corpus luteum is found, they talk about anovulation and send the woman first for examination to a gynecologist-endocrinologist, and then for treatment, since the reason for the absence of ovulation may be hormonal failure, and some pathologies of the ovaries, and other diseases and states.
If the corpus luteum is not found, this always indicates the absence of ovulation, which means that pregnancy in these cycles cannot occur in any way. But the discovery of the gland does not mean that the woman is pregnant - the corpus luteum exists in the second half of the cycle completely autonomously.
The detection of a corpus luteum shortly before the date of the expected next menstruation has its own nuances: if it is regressing, then this suggests that menstruation will soon begin, if nothing indicates regression, then pregnancy is quite possible. But the "interesting" position is not diagnosed this way - it is imperative that the doctor determines the presence of a fetal egg in the uterus, and before the 5th week of pregnancy it is almost impossible, given its meager size.
It's another matter after the delay. A well-visualized corpus luteum is an indirect sign of pregnancy, and can also indicate whether enough progesterone is produced to maintain pregnancy.
About sizes
Unlike the follicle, which, when monitored by ultrasound, changes its size every day in the first half of the cycle, the corpus luteum has a fairly stable size, normally constituting from 10 to 30 mm... A slight decrease in the days of the cycle is noticeable only in the regression stage, when the gland is absorbed. Therefore, do not worry if the doctor determines the diameter of the corpus luteum 11-12 mm, 13-14 mm, as well as 15-16 or 17-18 mm. Anything that fits within the range of 10 to 30 mm is normal size.
By the size of the corpus luteum with an accuracy of the day, the doctor will not be able to know when there was ovulation, given that the range of normal sizes is still quite large. It is believed that during the first week after ovulation, on average, the corpus luteum reaches 17-19 mm in size, 10 days after ovulation - 20-27 mm, and in the last five days of the cycle (if there is no pregnancy) it begins to decrease to 15 mm. Therefore, it is a stretch to say that a diameter of 21-22 mm corresponds to the ovulation period of 7-9 days, and a diameter of 23-24 mm indirectly indicates ovulation about 10-11 days ago. In the flowering stage of the gland, when its size is maximum, there may be values of 25, 26-27 and 28-29 mm, but in this case it will be difficult to calculate when ovulation actually took place.
Considering that in women, the size of the corpus luteum may initially be within the normal range and small and large, then it is possible to say about the time of ovulation only if the doctor estimates the size of the corpus luteum at least every other day. In practice, such a survey is not necessary.
If the size of the gland is only 8-9 mm or less, this indicates an insufficiency of the corpus luteum. With her, carrying a child is under serious threat of interruption, because the small gland produces little progesterone. When the highest level of the norm (31, 32, 40 mm and more) is exceeded, they talk about a possible cystic formation, the so-called luteal cyst or corpus luteum cyst. Its diameter can be up to 80 mm.
Pathological conditions
You should not look for special tables of norms for the size of the corpus luteum, since they do not exist in medicine, since the parameters of the temporary gland are considered quite individual. This means that only a doctor should decipher the ultrasound protocol. Consider what pathological conditions can be detected by ultrasound examination of the ovaries and corpus luteum.
Failure
A fairly common problem, usually associated with a low level of progesterone production. Insufficiency of the corpus luteum phase can cause unsuccessful implantation even with successful fertilization, so pregnancy will not occur. In the early stages, this is fraught with miscarriage, frozen pregnancy. With chronic insufficiency of the luteal phase, a woman develops endocrine infertility.
Such a pathology may be indicated by the small size of the temporary formation on the ovary (less than 10 mm), a thin endometrium. But the diagnosis will be made only after the progesterone deficiency is confirmed by the results of a blood test. It is recommended, if you suspect that the corpus luteum is insufficient, to do it on the 16-19th day of the cycle for the first time, and after 2 days, repeat it.
Insufficiency is not a sentence. And today she is successfully treated... To do this, the doctor recommends a woman progesterone drugs - "Utrozhestan" or "Duphaston", there are drugs in creams, gels. In hospital treatment, an oily solution of progesterone is administered intramuscularly.
As soon as a woman succeeds in getting pregnant, she is under increased medical supervision, and it is recommended to continue taking progesterone preparations throughout the first trimester until the placenta forms.
Cystic formation, luteal cyst
A corpus luteum cyst is formed for reasons that are not always understood by doctors. It is believed that this can be influenced by the physical activity experienced by the woman, as well as physiological disruptions, for example, the absence of regression of the previous corpus luteum, as a result of which a cavity filled with fluid is formed - a cyst.
On ultrasound, cystic formations are well visualized and are large in size, but this should not scare you - in most cases, cysts dissolve by themselves in 2-3 cycles without surgical intervention.
The cyst can dissolve even during the onset of pregnancy, without having absolutely any effect on the process of bearing the fetus, on the development of the baby in the mother's womb.
Lack of corpus luteum and persistence
The corpus luteum may not be found at all in the presence of a follicle. This literally means that the rupture of the follicular membrane did not occur, the egg did not come out, there was no ovulation. In this case, the follicle is noticeable up to 10 days in a row after the expected day of ovulation, its size does not change, and therefore persistence is easily determined by ultrasound in dynamics. When such a follicle degenerates into a follicular cyst, the ultrasound doctor notes an increase in the size of the follicle.
In such a cycle, pregnancy will not occur, but prolonged delays in menstruation are possible. Treatment is prescribed by a doctor - most often hormonal agents are used for therapy.
After the elimination of the persistent follicle, a woman's ability to conceive and reproduce is usually fully restored.
Conclusions
Doing an ultrasound scan to detect the corpus luteum and its size is not necessary for everyone and not always. Usually, such an examination is indicated for women with infertility, menstrual irregularities to determine the consistency of its phases, as well as for women who have undergone the procedure for stimulating ovulation with hormonal agents, followed by natural conception.
