Frozen-thawed epididymal spermatozoa for intracytoplasmic sperm injection

Objective: To report the fertilization rate and pregnancy results for intracytoplasmic sperm injection (ICSI) cycles using frozen-thawed epididymal spermatozoa. Design: Retrospective analysis of consecutive ICSI cycles. Setting: Tertiary referral center for infertility. Patient(s): Infertile couples in whom 39 patients (59 ICSI cycles) required the use of frozen- thawed epididymal spermatozoa. As no cycles were performed using fresh epididymal spermatozoa, outcomes were compared with those of 130 couples (170 ICSI cycles) using fresh ejaculated spermatozoa for severe oligoasthenozoospermia-teratozoospermia, in which <200,000 motile spermatozoa were retrieved after Percoll density gradient centrifugation. Intervention(s): Epididymal sperm aspiration during microsurgery, followed by ICSI. Main Outcome Measure(s): Fertilization, embryo cleavage, ET, and clinical pregnancy rates (PRs). Result(s): A total of 484 metaphase II oocytes were injected with frozen-thawed epididymal spermatozoa, resulting in a two-pronuclear fertilization rate per injected metaphase II oocyte of 47%, significantly lower than in cycles using fresh ejaculated spermatozoa (73%). Embryo implantation rates (12.0% versus 13.3%) and clinical PRs per transfer (18.4% versus 27.0%) were not different. When the prefreeze vitality was >20%, compared with lower vitality, both the fertilization (56% versus 22%) and embryo cleavage (91% versus 57%) rates were significantly greater. Conclusion(s): The routine collection and cryopreservation of epididymal spermatozoa at microsurgery allows multiple ICSI treatment cycles with success rates similar to those of ejaculated spermatozoa. However, when the vitality of aspirated spermatozoa is <20%, the poor fertilization rates indicate the need to consider an alternative source of viable spermatozoa.