Detection of ovulation and studying the menstrual cycle
The menstrual cycle is studied to determine the functioning of the ovaries with regard to pregnancy.
Egg release, or ovulation, is a basic prerequisite for the onset of pregnancy. Ovulation disorders typically cause menstrual cycle disorders, prolongation of the cycle or an absence of menstruation altogether. We confirm that ovulation occurs with additional examinations in connection with infertility examinations, even if the menstrual cycle is regular. The normal menstrual cycle is 23–35 days. The strongest ovarian follicle begins to separate from the rest in the first days of the menstrual cycle. The length of the follicular growth phase varies. In contrast, the normal length of the luteal phase after ovulation, during which the ovarian follicle is released, is 12–14 days without pregnancy. Once released, the egg is fertile for only 24 hours, but sperm are usually fertile in a woman’s body for at least three to four days. Thus, in normal circumstances, intercourse every two to three days during a normal cycle is sufficient for the onset of pregnancy without the need to find out the exact time of ovulation.
At the beginning of the menstrual cycle, around days 3 to 5 of the cycle, we will examine the levels of luteinising (LH) and follicle stimulating (FSH) hormones with a blood test. The tests are particularly important if there are any menstrual cycle disorders. The most common diagnosis for a patient with menstrual disorders is polycystic ovarian syndrome (PCOS). In this syndrome, the LH/FSH ratio may be higher than usual. PCOS diagnosis is supported by irregular cycles, acne, abundant hair growth and findings indicating PCOS in an ultrasonography. A high FSH level at the start of the menstrual cycle may indicate reduced ovarian function capacity.
A vaginal ultrasonography is performed around the 10th day of the cycle. In this phase of the cycle, the release of the strongest ovarian follicle has begun and it is possible to measure its size in an ultrasonography and determine the time of ovulation. We provide instructions for performing an ovulation test. We also examine the thickness and structure of the endometrium at this time.
When the ovarian follicle is large enough, about 20 mm, it causes intense secretion of the luteinising hormone (LH), which can be identified in the urine by ovulation tests. The tests can be taken at home and they are relatively reliable. An ovulation test is positive one to two days before the egg is released.
After the ovarian follicle is released, the luteal phase begins. In the luteal phase, the burst ovarian follicle must produce enough progesterone for the pregnancy to begin. The progesterone level is measured one week after a positive ovulation test. In a normal 28-day menstrual cycle, this measurement takes place on days 21–23 of the cycle. Signs of ovulation include the corpus luteum and a densely textured endometrium, which can be seen in an ultrasonography.
Learn more: Female infertility
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