1. What are the indications for follicle monitoring? What should I be aware of during follicle monitoring? 2. What are the criteria for a dominant follicle? What are the criteria for mature follicles? 3. What should be done for luteinized unruptured follicle syndrome? Follicular monitoring is an important method of diagnosis and treatment for both patients with abnormal ovulation and for finding the cause of menstrual abnormalities. Therefore, follicle monitoring is now widely used in the management of obstetrical and gynecological diseases. It is the best way to objectively reflect the growth and development of follicles, to observe whether ovulation is occurring, and to simultaneously reflect the development of the endometrium. The following is an overview of follicular monitoring. Indications for follicle monitoring 1. Infertility due to endocrine factors: such as menstrual disorders, anovulatory menstruation and amenorrhea, where follicle development is needed. 2. Polycystic ovary syndrome: PCOS is a common ovulation disorder with a complex etiology. In addition to non-ovulation leading to amenorrhea or menstrual irregularities, it can also present with signs such as hirsutism and obesity. Follicle monitoring can reveal that her ovaries are characterized by multiple small follicles but fail to develop to maturity. 3. Infertility due to premature ovarian failure: A common disease of ovarian dysfunction leading to non-ovulation is premature ovarian failure. Premature ovarian failure means that the follicles in the ovaries have been depleted and follicle monitoring is needed to understand ovulation and thus choose the appropriate method of conception. 4. Habitual miscarriage: follicle monitoring is needed to understand the growth and development of the follicles and the formation of the corpus luteum, which plays an important role in determining the specific cause of miscarriage and the clinical treatment plan. The dominant follicle On day 7 of the menstrual cycle, the follicle with the lowest FSH threshold among the group of developing follicles recruited is given priority to develop into the dominant follicle. A follicle >10 mm in diameter is generally referred to as the dominant follicle. The dominant follicle increases in size to about 18 mm by the 13th to 18th day of the menstrual cycle. The growth rate of the dominant follicle during the natural cycle is about 1 to 2 mm/d. The maximum growth rate of the follicles near ovulation can reach 2 to 3 mm/d. The follicles become mature when they reach 18 to 28 mm in diameter. Timing of follicle monitoring 1. Regular menstruation: Regardless of the length of the menstrual cycle, as long as menstruation occurs regularly and the difference between two menstrual cycles does not exceed 7 days, ovulation usually occurs about 14 days before menstruation. In women with normal menstruation, the luteal phase is fixed because the corpus luteum shrinks and decreases in function after about 14 days, while the follicular phase can be of uneven length. The first follicular monitoring can be done on day 11-12 of the menstrual cycle, and thereafter the next monitoring time will be determined by the size of the dominant follicle. When the size of the dominant follicle is 13-15 mm in diameter, the next monitoring interval is 2-3 days. When the diameter of the dominant follicle is greater than 16 mm, the next monitoring interval should be 1 to 2 days. 2. Irregular menstruation: Follicle monitoring should start on the third day of menstruation and be intermittent or continuous for a long period of time because the follicular phase cannot be determined from the menstrual phase and the monitoring time should be extended. Common causes of anovulation 1. ovarian failure: characterized by elevated blood FSH levels and low estrogen levels, due to congenital gonadal insufficiency or ovarian dysplasia and premature ovarian failure Hypothalamic-pituitary dysfunction: This is characterized by an abnormal ratio of gonadotropin LH to FSH secretion, such as in polycystic ovary syndrome, where the frequency and magnitude of LH secretion is abnormally increased, while FSH secretion is relatively insufficient, resulting in an inverse LH/FSH ratio. In these patients, estrogen levels are equivalent to early and mid-follicular levels. Polycystic ovary syndrome is the most common cause of anovulation in women. It is characterized by an enlarged ovary with multiple small follicles that do not develop to maturity and therefore require medications to promote follicular development. Hypothalamic-pituitary failure: Hypogonadism is characterized by low blood LH and FSH and estrogen levels and is called hypogonadotropic hypogonadism. 4. hyperprolactinemia: in patients of reproductive age, there is no ovulation or a shortened luteal phase, manifested by scanty, scanty or even amenorrhea menstruation and suppressed LH and FSH secretion. Pharmacological interventions during follicular monitoring 1. For ovulation induction, start on days 2-6 of the menstrual cycle. The recommended starting dose of gonadotropin hMG or FSH is no more than 75 IU/d, administered intramuscularly every other day or daily. If the ovaries do not respond after 7-14 days, gradually increase the dose (by 50% or l00% of the original dose) and keep the dose unchanged if a dominant follicle develops. HCG is generally For ovulation triggering in mature follicles, 5000-10,000 IU injected to simulate endogenous LH peak and predict ovulation timing. For patients on a long protocol of GnRH-a for controlled ovarian stimulation, the initiation dose of gonadotropin needs to be determined by a combination of the patient’s age, basal sinus follicles, basal FSH and body surface area. Generally, 225-300 IU/d can be initiated in patients ≥35 years of age, 150-225 IU/d or lower in patients 30-35 years of age, and 112.5-150 IU/d in patients <30 years of age. Ultrasound monitoring of follicular development and blood estrogen levels after 4 to 5 days of dosing. Adjust gonadotropin dosage according to follicle number, follicle diameter and blood FSH, LH and E2 levels. When two to three dominant follicles reach 18 mm in diameter and the average E2 level per mature follicle is 200-300 ng/L, hCG 5000-10000 IU or rhCG 0.25 μg is injected and eggs are retrieved 36-38 hours later. 3. Teinized Unmollicized Follicle Syndrome (LUFS): a special type of anovulatory menstruation in which the follicles mature but do not rupture and the oocytes are not expelled but luteinize in situ, forming the corpus luteum and secreting progesterone, causing a series of changes in the body's effector organs that resemble the ovulatory cycle. The prevalence of LUFS in women of normal reproductive age has been reported to be 5-10%. In women with infertility the incidence is 25 to 43%. In this case, HCG 5000-10,000 IU can be given after monitoring the maturation of the follicles. If the follicle has not collapsed or disappeared by ultrasound after 48 h of HCG injection, the follicle can be squeezed gently with the mechanical cooperation between the ultrasound probe and the hand. If ovulation does not occur, ultrasound-guided puncture is indicated. The diagnostic criteria for LUFS are as follows: (1) Basal body temperature is typically biphasic. (2) Regular menstruation with elevated luteal phase blood progesterone level. (3) Cervical mucus or endometrial biopsy with normal tissue secretion phase. (4) Continuous B-ultrasound tracing of follicles with mature follicles but no ovulation (Vaginal B-ultrasound is performed from the 5th day of menstruation and every 1 to 2 days thereafter to observe follicular development, no sign of ovulation after prediction of ovulation, follicles continue to grow or exist after intramuscular injection of HCG 10000 U. After 3 to 4 cycles without pregnancy, IVF can be considered. Follicle monitoring considerations 1. Ovulation monitoring should be done in conjunction with endometrial thickness monitoring to understand endometrial and ovarian homeostasis and endometrial status. 2. 2. Ovulation monitoring should be evaluated in combination with basal body temperature, cervical mucus and hormones. Attention should also be paid to luteal monitoring as many patients have combined luteal insufficiency. 3. Basal body temperature to monitor ovulation: Measure and record the body temperature every morning before waking up. If the temperature changes in a biphasic pattern, it indicates ovulation; if there is a monophasic pattern without a late rise in the temperature curve, it indicates no ovulation. Generally, the body temperature rises by about 0.5℃ during the luteal phase after ovulation and lasts for more than 10 days. LH monitoring for ovulation: The sharp pulsatile secretion of LH in the mid-menstrual period can be used as a reference point for the time frame of approaching ovulation. Several studies have reported that ovulation usually occurs around 24 h after the onset of urinary or blood LH. Small follicular ovulation: The development of the dominant follicle is generally considered to be mature when the mean of the three follicles ≥ 18 mm. This may be due to insufficient pituitary gonadotropin secretion and/or an early onset of the LH peak. In small follicles, the follicular dysplasia leads to decreased fertilization of the oocytes or, although fertilization can occur, further differentiation and development is reduced, resulting in infertility or recurrent spontaneous abortion. Ovulation promotion is an effective treatment for small follicle ovulation, and treatment with ovulation-promoting drugs can increase pregnancy rates and improve pregnancy outcomes. The detection of small follicle ovulation should be started on the 7th to 9th day of menstruation and monitored every other day and daily when the mean follicle diameter reaches 15 mm. As a rule, the number of ultrasound monitoring should be limited to 3 to 4 times per cycle. 7. Ultrasound monitoring for follicular disappearance or collapse after the body temperature rises in natural cycles. In ovulation or IUI cycles, when the follicle is >18-20 mm, it indicates that the follicle has matured and can be injected with HCG and monitored 48 hours later to see if the follicle has expelled. 8. In the presence of >3 dominant follicles at the time of ovulation induction, it is recommended to cancel the cycle treatment. 9. The time of conception: from 3 days before ovulation to 1 day after ovulation, you can try to conceive and it is not necessary to limit the time of intercourse.