Improved results of thawed sperm cryopreserved with slow stage: Cooling with a cellevator

There is a need to develop a sperm cryopreservation technique that will allow good pregnancy rates following intrauterine insemination of thawed semen specimens that have been frozen prior to sperm-destructive procedures, such as surgery, chemotherapy, or radiation therapy. A slower cooling rate using a commercial semiprogrammable freezer may provide improved post-thaw motility and hypoosmotic swelling (HOS) test scores. However, the cost of this apparatus precludes it from being used in most andrology centers. This study compares the efficacy of slow stage cooling using an inexpensive cellevator (a device used to freeze lymphocytes) to liquid nitrogen vapor freezing. The semen from 27 males was equally divided and one aliquot was cryopreserved with the cellevator stage cooling and the other with the liquid nitrogen vapor technique. The percent motility and percent grade A sperm post-thaw were significantly higher when cryopreserved with the cellevator than with vapor freezing, as was the mean percentage of sperm showing HOS changes.