There are many causes of infertility, but they can be roughly divided into the following 6 types: 1. tubal problems and pelvic adhesions; 2. male semen problems; 3. ovulation problems; 4. endometriosis; 5. congenital and acquired abnormalities of the cervix, vagina and uterus itself; Yu Qi, reproductive endocrinology of Peking Union Medical College Hospital 6. unknown causes. So the examination of infertility should be carried out from these putative aspects first. Male semen examination: very critical and should be performed first. Tubal examination: Its etiology can be pelvic tuberculosis, pelvic inflammatory disease, history of tubal surgery, etc. The examination methods for tubal and pelvic adhesions include lavage, imaging and laparoscopy plus hysteroscopy. 60% of pregnancies occur within six months after the examination. Therefore, it is important to make sure that the male partner’s semen is normal before performing any of the tubal tests in order to make the most of the six months after the test. If pregnancy is still not possible after six months of a particular tubal test, the next test should be performed. In principle, the sequence of lavage – hysterosalpingogram – laparoscopy should be followed. If you are older, you may consider skipping the lavage and/or imaging; if you suspect uterine malformation or tuberculosis, you may give priority to imaging; if you suspect endometriosis or pelvic adhesions, you may give priority to laparoscopy; if the surgery fails or you are still infertile after the surgery, consider IVF. Ovulation tests: basal body temperature is the simplest and most effective method, which can observe luteal function in addition to the presence or absence of ovulation; determination of progesterone levels during the luteal phase is also a method, but it is not accurate enough and is also troublesome; ultrasound monitoring of follicle development is the gold standard for ovulation tests, but it is also the most troublesome method, requiring frequent or even daily ultrasound. Endometriosis: laparoscopy is the means to confirm the diagnosis, other methods can only be speculated. It is important to point out here: the various antibody screening methods that are widely popular are not very reliable, not that the problem of various antibodies does not exist, but there is no accurate way to monitor these antibodies, and the accuracy of the existing methods is very poor and cannot be used as an effective clinical examination, so there are still a considerable number of patients who have undergone laparoscopy and still have not found the cause, which is unexplained infertility .