Published online by Cambridge University Press: 01 February 2010
The clinical use of frozen-stored human semen or sperm is practical, beneficial, safe and it provides a readily available method for the treatment of infertility and the preservation of fertility. It was known in the eighteenth century that sperm could survive freezing. However, the first published report of successful insemination of cryopreserved sperm did not appear until 1954. Since then, improvements in cryoprotectant media and freezing protocols have made sperm cryopreservation applicable for all aspects of therapeutic insemination. When human chorionic gonadotropin (hCG) injection or luteinizing hormone (LH) timing and equal numbers of progressively motile donor sperm are used for intrauterine insemination, there is no difference in pregnancy rates between fresh and cryopreserved sperm. Most clinical practices that perform large numbers of inseminations with fresh sperm will wish to be able to cryopreserve patient sperm. If a clinical practice does not itself perform cryopreservation it may still refer patients to clinics or laboratories that do, and arrange for the cryopreserved specimen to be returned to the practice for thaw and insemination, as would be done in a case of donor insemination.
The advantages of frozen sperm over fresh sperm are many (Table 11.1). Cryopreservation provides the means to disassociate sperm collection and processing from ovulation. It is always available for use. For men with low total sperm counts several ejaculates can be frozen and combined later. Conversely, for men with high total sperm counts a single ejaculate can be used in several insemination cycles if they are not always available to furnish a fresh specimen.