Swim-up

Sperm washing is the process in which individual sperms are separated from the semen. Washed sperm is used in artificial insemination using the intrauterine insemination (IUI) technique and in in vitro fertilization (IVF). It may also be used to decrease the risk of HIV transmission by an HIV-positive male, in which case the washed sperm is injected into a female using an artificial insemination technique.

Sperm washing involves removing any mucus and non-motile sperm in the semen to improve the chances of fertilization and to extract certain disease-carrying material in the semen. Sperm washing is a standard procedure in infertility treatment.

Sperm washing takes place in a laboratory following sperm donation.

Sperm may be washed by density gradient centrifugation or by a "direct swim-up" technique that does not involve centrifugation. In normal semen samples, centrifugation causes no more DNA damage to spermatozoa than a direct swim-up technique.

Washed sperm is concentrated in Hams F10 media without L-glutamine, warmed to 37 °C (99 °F). A chemical known as a cryoprotectant is added to the sperm to aid the freezing and thawing process. Further chemicals may be added which separate the most active sperm in the sample, as well as extend or dilute the sample so that vials for a number of inseminations are produced.

Sperm washing can be used to decrease the risk of HIV transmission in HIV-positive males, because the infection is carried by the seminal fluid rather than the sperm. One Italian study from 2005 of 567 serodiscordant couples treated with washed sperm resulted in no horizontal (to the woman) or vertical (to the child) HIV seroconversion. However, there is no 100% guarantee that washed sperm is free from the virus.

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Wikipedia