THE CRYOPRESERVATION OF DONOR SEMEN BY A SIMPLIFIED METHOD - USE IN AN IVF AND GIFT PROGRAM

The cryopreservation of semen used in assisted reproduction procedures was carried out exclusively by a simplified method in which a mixture of semen and cryoprotectant was contained in 1‐ml tuberculin syringes and plunged directly into liquid nitrogen. Donor semen samples halved and frozen in syringes and in straws in a controlled‐rate freezer showed no significant difference in post‐thaw motility (P=0.217) or survival (P=0.217) after 30 min. However, after 180 min the survival rate showed a significant reduction in syringes (P=0.045). A significant difference (P<0.00008) in the rate of fertilization of oocytes was seen in IVF cycles using frozen‐thawed donor sperm (58/142, 42%) when compared to fresh sperm from husbands (2315/3926, 59%). A significant reduction (P<0.00005) in fertilization rate was also observed in the case of supernumerary oocytes in GIFT cycles with the cryopreserved donor sperm (29/132, 22%) compared to the husbands' sperm (239/514, 46%). However, the pregnancy rate following IVF and embryo replacement was the same after fertilization with fresh sperm (75/351, 21%) as opposed to frozen sperm (3/14, 21%). Furthermore, a higher pregnancy rate was observed in GIFT with frozen donor sperm (9/19, 47%) than with fresh sperm from husbands (28/103, 27%), though this was not statistically significant (P=0.079). These results show this simplified method of semen cryopreservation to be effective when used in an IVF and GIFT programme, giving pregnancy rates comparable to fresh normo‐spermic semen samples. The method is simple, quick and inexpensive. Copyright © 1990, Wiley Blackwell. All rights reserved