Cryopreservation of human spermatozoa: The effect of cryostorage time on the post – thaw sperm outcome.

ABSTRACT

A prospective study was reported comparing the effect of short-term (1 week) and long-term (6 months) cryostorage time on the post-thaw sperm outcome in four different freezing techniques. Eighty five semen samples were included in the study. Each sample was divided and subjected to four cryopreservative techniques CEG-NCR, CEG-CR, TEST-EYG-NCR, and TEST-EYC-CR. The cryopreservation of each technique was performed in similar way by mixing the semen with the cryopreservative media (CEG or TEST-EYG) in ratio 11, then the mixture was aspirated into two straws. The temperature was then reduced (by NCR or CR freezing method) to -80 C, then the straws were transferred into liquid nitrogen. One straw of each technique was thawed after 1 week and the other straw after 6 months of cryostorage time for assessing the post-thaw sperm outcome. As the results, the post-thaw sperm motility and survival rate of the 1 week cryostorage group was slightly higher than the 6 months group in the CEG-NCR and the CER-CR freezing technique, but these did not have clinical significance because the differences were into small. There were no differences of post-thaw sperm outcome between 1 week and 6 months group in the TEST-EYG-NCR and TEST-EYG-CR freezing techniques. We concluded that the duration of cryostorage did not have clinical effect on the post-thaw sperm outcome.