What is sperm washing, and why is it done? During intrauterine insemination, sperm is inserted directly into the uterus with a special catheter. This cuts out part of sperm's normal journey: the vagina and the cervix. During those swimmers' usual journey, some chemicals that were part of semen are filtered out. This would not happen with sperm inserted directly into the uterus, so sperm is instead washed by your fertility clinic.
Sperm washing filters out prostaglandins, male chemicals that can cause uterine contractions. If "raw", unwashed sperm, were to be inserted into the uterus, it was cause heavy cramps and pain. But that is not all sperm washing does; that process also gets rid of substandard quality and dead sperm that may be part of your partner's semen sample.
Sperm washing can even be used to prevent the transmission of the HIV virus (fertility treatments to prevent spread of HIV safe)! Although the sperm washing process is mainly associated with intrauterine insemination treatment, the procedure can also benefit others. Men with morphology problems may have their sperm washed without IUI there is also the option of transvaginal insemination. And women who have endometriosis increase their chances of getting pregnant when their partner's sperm has been washed.