Why is it necessary to treat fluid in the fallopian tubes before IVF treatment? Since the birth of “test-tube” babies more than 20 years ago, human assisted reproduction technology has evolved greatly. Especially in recent years, because of the maturity of various technologies, including the perfection of cell culture fluid and the rich experience of medical personnel, the success rate of IVF has gradually increased worldwide, from about 20%-25% to 30% or even higher. The literature shows that tubal effusion reduces the pregnancy and fertility rates of IVF by 50% and increases the miscarriage rate by a factor of 2. In other words, if the success rate of IVF is 20-30%, the success rate will be 10-15% if there is tubal effusion, and the miscarriage rate will increase, so it is crucial to treat tubal effusion before IVF treatment. The reasons for this are as follows: 1. The fluid retention in the fallopian tube changes the internal environment of the uterine cavity and mechanically interferes with the contact between the embryo and the endometrium. 2. The microorganisms, debris and toxic substances contained in the fluid in the fallopian tube affect embryo implantation, reducing the embryo implantation rate and pregnancy rate and increasing the miscarriage rate. The cytokines, prostaglandins, leukocyte chemotactic factors and other inflammatory complexes released by the tissue in hydrocele affect the endometrium and embryo implantation. 4. Patients with hydrosalpinx have decreased endometrial beta-one integrin levels during the implantation window, which can also affect endometrial tolerance. 5. Tubal effusion is often caused by infections, mostly upstream infections, which may cause endometrial damage and leave permanent effects on embryo implantation tolerance. 6. Ultrasound monitoring during IVF treatment may reveal a few tubal effusions with progressive enlargement, which may be mistaken for developing follicles and may lead to misleading medication and early administration of HCG, resulting in a decrease in the rate of mature oocytes during egg retrieval. 7. On the other hand, the fluid in the fallopian tube is mistakenly penetrated during transvaginal egg retrieval under ultrasound monitoring, and the fluid directly contaminates the oocytes and affects the fertilization of oocytes and the development of fertilized eggs. Therefore, in order to improve the success rate of IVF and reduce the miscarriage rate, it is necessary to start treating the hydrocele in the fallopian tubes.