Recently, Xiao Zhang was preparing to get pregnant. After trying for a few months without seeing any improvement in his wife’s condition, he noticed that his semen would pour out of his wife’s body after every intercourse. Thinking that this was the main cause of his wife’s infertility, Zhang came to the clinic in frustration and asked the doctor if there was something wrong with his semen. After taking a careful medical history, the doctor explained to Zhang that semen leakage after intercourse is actually a normal phenomenon. In order to understand this problem, let’s first have a proper understanding of semen. Semen includes spermatozoa and seminal plasma, which is composed of secretions from the epididymis, seminal vesicles, prostate and urethral bulbous and paracrine glands. After male ejaculation, semen will be stored in the posterior vaginal fornix (the junction with the uterus) of women, the cervix and its secretion of mucus is like a barrier, only healthy and viable sperm in the semen through the tail of the rapid swing to the cervix direction of fast movement, and with the help of the uterus contraction and tubal peristalsis through the cervical mucus, through the uterine cavity, and finally reach the fertilization site, that is, the juxtaposition of the tubal tubes. And those deformed sperm, low mobility or dead sperm and other components of semen can not enter the uterine cavity through the cervix. If prostate fluid enters the uterine cavity, it contains prostaglandins that can stimulate uterine contractions and cause abdominal pain. What about the role of seminal plasma? It is a carrier of sperm from the male reproductive tract to the female reproductive tract and a buffering substance. The alkaline nature of seminal plasma neutralizes the acidity of the vaginal fluid and therefore protects the sperm from damage. Some components of seminal plasma, such as fructose, can also provide nutrients and energy for sperm and also maintain a certain osmotic pressure, which is conducive to the survival of sperm. So why how come the semen that is ejaculated into the vagina flows out of the vagina backwards? After normal sex, sperm quickly leave the semen pool in the posterior fornix and enter the cervical canal, while the seminal plasma that remains in the vagina after completing its mission either overflows out of the vagina or is degraded by enzymes in the vagina. At the same time, the outflow of semen is also related to the position of the body during intercourse, the size of the vaginal capacity, the amount of semen and semen ejaculation into the site and ejaculation too fast. The woman lying on her back with her legs straight, the vagina and the horizontal position constitutes a small angle, due to the role of gravity semen is also easier to flow out of the body. Therefore, if the wife’s vaginal volume is smaller, or the husband ejaculated more semen, ejaculation into the site and shallow (such as some patients with hypospadias ejaculation is too shallow), it is more likely to semen overflow phenomenon. And with the seminal plasma outflow are also deformed and inactive spermatozoa as well as fluid produced in the female genital tract during sexual arousal. However, to ensure that as many sperms as possible enter the cervix, the buttocks can be elevated after intercourse to avoid premature spillage of semen into the vagina, which may affect the chances of conception. After listening to the doctor’s explanation, Zhang was relieved and went home to follow the doctor’s instructions to elevate his wife’s hips after intercourse and continue to try to conceive, and it wasn’t long before he heard that his wife was expecting.