Human spermatozoa have been successfully frozen since 1953. Sperm, in general, can be frozen indefinitely. Indications for freezing sperm include:
- Preservation of reproductive potential before chemotherapy, radiation, or surgery
- Availability of spermatozoa at the time required for infertility treatment, absence of male partner, performance anxiety, previous poor semen at on-demand occasions
- Storage of sperm before vasectomy
- Preservation of spermatozoa after surgical intervention to obtain sperm, i.e. microsurgical epididymal sperm aspiration or testicular sperm extraction in cases of azoospermia
Successful cryopreservation is dependent on the quality of semen cryopreserved. In general, high counts with good motility freeze well with acceptable rates of sperm recovery following thawing. Semen of poor initial quality may render very few sperm with thawing, such that ICSI in vitro fertilization may be the only realistic option of using that semen.
If cryopreservation of semen is employed for donor use, a strict protocol including screening for transmissible diseases including AIDS and hepatitis and an appropriate quarantine period is mandatory.