Sperm washing is a procedure that is closely associated with Intrauterine Insemination (IUI). There are various types of sperm washing, ranging from a straightforward sperm was to prepare the sperm for IUI, to a HIV sperm wash that is aimed at preventing the spread of HIV to a negative partner and the baby.
IUI and sperm washing Intrauterine Insemination is suitable for couples who had trouble getting pregnant because of female ovulation issues, or a slightly low sperm count. Single women or those otherwise using a sperm donor also usually turn to IUI. During the IUI procedure, sperm is inserted directly into the uterus. Semen contains prostaglandins, chemicals that would make the uterus contract heavily and painfully. These prostaglandins are eliminated from the semen in a sperm washing process.
A simple sperm washing process involves a centrifuge, protein supplements, and antibiotics. It results in a concentrated sperm sample ready for IUI. In contrast,a density gradient sperm wash also gets rid of dead sperm and other waste products. This results in a higher chance of success. Then there's a "swim up" sperm wash technique, which is designed to catch only the healthiest sperm. This involves the sperm swimming up to a culture placed at a higher level, mimicking the natural process where sperm have to move up to reach the uterus.
HIV and sperm washing IUI sperm washing techniques are relatively low-cost, and mostly covered by insurance as well. Couples in which the man is HIV positive, while the woman is negative, may find hope in HIV sperm washing. The procedure, which was developed in Italy, is based on the idea that the transmission of HIV goes mainly through seminal fluid, rather than the sperm themselves. The procedure is expensive, not covered by insurance, and not available everywhere. Couples who are interested may be able to get this financed because research is still ongoing. Success rates are quite high, as far as I have read, but those who are seriously considering HIV sperm washing should look into the statistics and be aware that getting HIV is not completely impossible with this procedure.