The current national and World Health Organization definition of infertility is that a couple (husband and wife) who have had normal sexual intercourse without contraception for at least 12 months are infertile in the woman and infertile in the man. Couples who have never been pregnant in the past are considered to have primary infertility, while those who have had a history of pregnancy in the past are considered to have secondary infertility. In fact, this concept is very difficult to define in reality. For example, if there is a remarried couple, the woman has a history of miscarriage or childbirth, while the man has no history of childbearing, should we call the woman secondary infertility and the man primary infertility? Infertility is one of the most common problems in the field of reproductive health, with a prevalence rate of about 10-15% of couples of childbearing age. For infertile couples who visit us for the first time, we can initially screen for the cause of their infertility through a four-step examination. Step 1 Routine male semen analysis Routine semen analysis is simple, convenient and inexpensive, so it is used as the first line of initial screening. If the indicators are normal, it is more reasonable to proceed with the examination of the woman. Some husbands are a bit chauvinistic, or too shy, think they are strong, not willing to do the examination first, the clinic often encountered the female side of the examination of a large circle, but in the end it is the male side of the cause of the situation. The second step of gynecological pelvic examination For the first time to see the infertile female patients need to do a careful gynecological examination in the non-menstrual period, to understand the size of the uterus, location, texture, mobility, uterine sacral ligament root with or without tenderness and nodules, bilateral adnexa with or without abnormal thickening and pressure pain. If abnormal pelvic signs are found, combined with clinical symptoms, infertility due to pelvic factors can be further determined. For example, if the uterosacral ligament is found to have tenderness and nodules, and pelvic endometriosis is suspected, laparoscopy can be done to make a clear diagnosis. Step 3 Ovulation monitoring Commonly used methods to monitor ovulation include basal body temperature (BBT), vaginal ultrasound to monitor ovulation, and serum sex hormone measurement. BBT is a simple self-monitoring method to know whether a woman is ovulating or not. For women with regular menstrual cycles, continuous monitoring of BBT from the first day of the menstrual cycle to the next menstrual period can retrospectively find out whether there is ovulation in the previous cycle and whether the luteal function is insufficient or not. biphasic type of BBT suggests that there is ovulation, and monophasic type indicates that there is no ovulation. For infertile women with poor ovulation and anovulation, serum sex hormone measurement can be performed. Generally, serum follicle stimulating hormone (FSH), luteinizing hormone (LH), prolactin (PRL), estradiol (E2), and testosterone (T) are measured on days 2-3 of menstruation to understand the ovarian reserve status; and serum progesterone (P) level is measured during the second half of menstruation to determine the presence or absence of ovulation and to understand the luteal body function. Infertile women who can have poor ovulation and anovulation can undergo serum sex hormone measurement. Generally choose in the second to third day of menstruation, measurement of serum follicle stimulating hormone (FSH), luteinizing hormone (LH), prolactin (PRL), estradiol (E2), testosterone (T), to understand the status of the ovarian reserve, and measurement of the level of serum P to determine the presence or absence of ovulation, as well as to understand the function of the luteal body after ovulation. Step 4 Tubal patency test Hysterosalpingography (HSG) is the recommended and commonly used method to check tubal patency. A contrast medium is injected into the uterine cavity and fallopian tubes through a contrast tube, and the passage of the contrast medium through the uterine cavity and fallopian tubes is observed under X-ray fluoroscopy and X-ray film is taken to find out whether the tubes are patent and the shape of the uterine cavity, with an accuracy rate of up to 80%. Contrast agents include oil (iodized oil) and water-soluble (pantethine glucosamine, iohexol). Iodized oil has high density, good visualization effect, and some therapeutic effects on the fallopian tubes. Laparoscopic tubal fluid test is more intuitive, and its accuracy rate reaches 90~95%. Tubal patency test is more accurate and reliable under the combination of hysteroscopy and laparoscopy. Because laparoscopy is invasive and requires special surgical instruments, it is expensive and cannot be used as a routine screening tool, and is usually only used when there is a suspicious pelvic condition that is valuable for diagnosis and treatment. If none of the above four steps reveal a problem, it is called unexplained infertility. This does not mean that there is no cause, but rather it indicates that meaningful tests have not found a cause at this time, and that some of these patients simply have low fertility and can occasionally get pregnant on their own. Some couples end up having to go through IVF in vitro fertilization techniques to discover the cause of infertility.