Cryopreservation of epididymal sperm

Abstract

The advent of ICSI and the perfecting of freezing protocols for sperm samples that in the pre-ICSI era would not have been frozen, allows now routine cryopreservation of epididymal sperm regardless of their quality and quantity. There are two methods to retrieve epididymal sperm: microsurgical epididymal sperm aspiration (MESA) and percutaneous epididymal sperm aspiration (PESA). The majority of the literature has focused on the technique of MESA to obtain sperm on the claim that the amount of sperm retrieved with PESA might not be sufficient to allow cryopreservation. However, there are no data on cryopreservation and ICSI with epididymal sperm collected with PESA technique. In this study, a total of 68 consecutive cycles of PESA, of which 46 were performed with fresh epididymal sperm and 22 with frozen/thawed specimens were retrospectively analyzed. In the fresh epididymal group ( n=46), 446 eggs were injected and 207 cleaving embryos were obtained (fertilization rate of 46%). In the cryopreserved epididymal sperm group ( n=22), 216 eggs were injected and 115 cleaving embryos were obtained (fertilization rate of 53%, P=NS). There were 18 pregnancies (39%) with 17 (37%) delivered/ongoing in the fresh group, while there were 11 (50%) with 9 (41%) delivered/ongoing in the frozen group ( P=NS). Epididymal sperm for cryopreservation was available in 44 of the 46 PESA cycles. Additionally, in the fresh group, 19 couples had excess embryos for cryopreservation while in the frozen group, ten couples had excess embryos for cryopreservation. A total of 17 frozen embryo transfer with epididymal sperm from PESA were analyzed. Of these, 12 FET were from embryos from the fresh epididymal group and three pregnancies with livebirths (25%) were recorded. Five FET were performed with extra embryos from frozen epididymal sperm and two (40%) pregnancies with livebirths were obtained. In summary, these data show that epididymal sperm obtained by PESA can be successfully cryopreserved in order to avoid future retrievals procedures and fertilization and pregnancy rates are similar between fresh and cryopreserved epididymal sperm. It is also reported for the first time that the transfer of frozen embryos obtained with either fresh or frozen/thawed epididymal sperm leads to the same pregnancy and delivery rate.