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Cryopreservation of sperm: indications, methods and results.

PURPOSE
We review the history of the cryopreservation of human sperm. The current methods of cryopreservation and indications are highlighted, and the success rates of the various uses of cryopreserved sperm are reviewed. Potential adverse sequelae of human cryopreservation are also discussed.


MATERIALS AND METHODS
Indications for cryopreservation include several applications, namely homologous and donor insemination, cryopreservation prior to surgical infertility treatment, intraoperative cryopreservation, postoperative cryopreservation, cryopreservation prior to treatment for malignancies and nonmalignant diseases, as well as premortem and postmortem cryopreservation.


RESULTS
With the use of intracytoplasmic sperm injection, open microsurgical epididymal sperm aspiration and testicular sperm extraction with cryopreserved sperm in men with obstructive azoospermia yields pregnancy rates similar to those using fresh sperm. Intraoperative cryopreservation is recommended for complex reconstructive cases with lower patency rates, including vasoepididymostomy and vasoepididymostomy to the efferent ductule. In addition, sperm banking is strongly recommended for all patients with malignant disease who may wish to have children, since a small but significant percent of these men later use their banked semen. Although there is concern about the transfer of genetically damaged sperm after cryopreservation, no proven increase in genetic or phenotypic abnormalities in offspring has been identified.


CONCLUSIONS
Sperm cryopreservation has revolutionized the field of assisted reproduction. Cryopreserving sperm avoids the need for additional surgery in couples undergoing repeated in vitro fertilization/intracytoplasmic sperm injection cycles. Moreover, it provides hope for men undergoing chemotherapy, radiation or radical surgery who once had no chance for future fertility.