Luteal phase disorders
The luteal phase is the last phase of a woman's menstrual cycle. Its length is an individual feature. It is conditioned by many factors.
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1. When does the luteal phase occur?
The luteal phase of a woman's menstrual cycle is the time from the onset of ovulation until the first day of menstruation. In a normal cycle, its length ranges from 10 to 12 days. In this phase, the endometrium of the uterus, under the influence of the hormone progesterone, prepares for the implantation of a fertilized egg.
In luteal phase disorders, this time is shortened as a result of too low progesterone concentrations, and therefore the uterine mucosa is not properly prepared for pregnancy, which may prevent embryo implantation and lead to early miscarriage, often unnoticed, on the day of the expected menstruation. Disorders of the luteal phase can therefore become the cause of infertility in women and often require the use of appropriate therapy so that a woman trying to conceive a child could become pregnant.
2. Luteal phase of the menstrual cycle
The normal menstrual cycle is 28 plus or minus 4 days. This begins on the first day of your period and this is called the menstrual phase and lasts 1-5 days, when the endometrium peels off and bleeding occurs. Then the follicular phase begins and lasts from day 6 to day 13 of the cycle. In this phase, under the influence of FSH, several follicles grow and then one dominant follicle is removed from them. There is also a significant increase in the concentration of estrogens, which stimulate the reconstruction of the uterine mucosa, this membrane thickens, the number and volume of glands increases and its vascularity increases.
Around day 14, a sudden increase in LH levels causes ovulation, i.e. the release of an egg from the ovarian follicle. After ovulation, this follicle transforms into a corpus luteum, which, when stimulated further by LH, produces progesterone. This is the luteal phase of the cycle that lasts from day 15 to day 28 of the cycle.
Increasing concentrations of progesterone, the peak of secretion of which falls on the 22-23 day of the cycle, causes a further increase in the thickness of the mucosa, the glands become wider and have a wavy shape, the glandular epithelium thickens, the stromal connective tissue is swollen, and the cells accumulate glycogen, lipids and proteins . All this is to prepare the embryo for implantation. If fertilization does not take place, the concentration of progesterone decreases, which leads to degenerative changes in the endometrium and, as a result, to its peeling during menstruation.
3. Diagnosis and treatment of luteal phase disorders
In the case of suspicion of luteal phase disorders, the determination of its duration is of fundamental importance for making such a diagnosis. Basal body temperature is most often used for this, because on the day of ovulation, a woman's body temperature rises by about 0.5 degrees Celsius and this continues throughout the luteal phase until the onset of menstruation. On this basis, the duration of the luteal phase is determined, which should normally be 10 to 12 days.
The second necessary premise for the diagnosis of luteal phase disorders is the detection of a decreased concentration of progesterone measured 7 days after the presumed ovulation. Both of these abnormalities, i.e. shortening of the lethal phase and low progesterone concentrations, authorize the diagnosis of luteal phase disorders.
This means that as a result of the too short duration of the luteal phase and too low progesterone concentration, the uterine mucosa is not properly prepared for embryo implantation. In such cases, treatment attempts are made to use progestogens and chorionic gonadotrophin throughout the second phase of the cycle to improve endometrial preparation. However, taking into account the fact that the correct function of the corpus luteum depends on the proper development of the ovarian follicle, anti-estrogens and gonadotropins are also used to stimulate its development. As a last resort, if this therapy does not help and the woman still cannot get pregnant, there are still assisted reproductive techniques.