Infertility is defined as a couple of childbearing age living together after marriage, having a normal sexual life and not having conceived for 2 years without contraception. It is estimated that the rate of conception in the first year after marriage is about 90%, while the value added in two years is about 95%, so routine examination and treatment are recommended for those who have not conceived for one year. Infertility is divided into primary and secondary. Those who have never conceived after marriage without contraception are called primary infertility, while those who have had a pregnancy and then have not conceived for two consecutive years without contraception are called secondary infertility. The incidence of infertility is about 8-10%. The diagnosis of infertility requires a comprehensive examination of both men and women to find out the causes, and the following examinations are briefly described for the female partner: 1. (1) Serological examination: follicle-stimulating hormone (FSH), luteinizing hormone (LH), estradiol (E2), testosterone (T), prolactin (PRL) and progesterone (P) are present in specific cycles during the menstrual cycle. Serum FSH, LH, E2, T, and PRL are measured on the second to fourth day of menstruation. FSH >10 U/L indicates ovarian hypofunction and >40 U/L indicates premature ovarian failure. If the serum P is greater than 16 nmol/L (5 ng/ml), it indicates ovulation, but less than 31.8 nmol/L (10 ng/ml) indicates insufficient luteal function. (2) Basal body temperature (BBT): Basal body temperature fluctuates under the influence of estrogen and progesterone and is the easiest way to diagnose ovulatory function. Measure the temperature under the tongue with a thermometer for 5 minutes after waking up from a deep sleep for at least 6 hours, and plot the temperature into a curve. The temperature of the ovulatory cycle is biphasic and will rise by 0.2-0.3°C for about 14 days after ovulation. (3) Ultrasound monitoring of ovulation: Ultrasound is usually performed on the second to fourth day of menstruation to exclude ovarian physiological cysts and other organic lesions and to help assess ovarian function; monitoring of ovulation begins on the ninth to tenth day to determine if follicles are developing normally. The follicles are usually larger than 18mm in diameter before ovulation and can be expelled normally. (1) Fallopian tube iodography is the most commonly used test, which is performed 3-7 days after menstruation. (2) Tubal lavage is the slow injection of saline into the uterine cavity. If there is no resistance and no reflux, it indicates patency of the fallopian tubes. Currently, tubal lavage is less commonly used because it is more subjective and does not clarify the site of tubal obstruction. (3) Laparoscopy is the most accurate means to evaluate the patency of the fallopian tubes. Melan solution is injected from the cervix and the fluid is observed through laparoscopy to see if it flows from the umbilical end of the fallopian tube. It also allows observation of pelvic adhesions and micro endometriosis lesions, which can be treated at the same time. (4) Some patients may require endometrial examination, such as endometrial biopsy to exclude endometrial tuberculosis in those with a history of tuberculosis. In the past, endometrial biopsy was usually scheduled within 12-24 hours of menstrual flow in order to understand ovulation and luteal function, but nowadays, the tests to evaluate ovulatory and luteal function are much better and endometrial biopsy is no longer necessary. In our center, endometrial biopsy is usually performed in patients with thin endometrium and uneven endometrial echogenicity before ovulation, scheduled during the implantation window (i.e. 5-7 days after ovulation), which is the period of embryo implantation into the endometrium, in order to exclude endometrial inflammation and some other changes that affect embryo implantation. The requirement for this test is to abstain from intercourse during the month of the test.