Fertilization capability of frozen epididymal sperm for intracytoplasmic sperm injection.

Both microsurgical epididymal sperm aspiration (MESA) and intracytoplasmic sperm injection (ICSI) are great advances in assisted reproductive techniques. By using the ICSI technique, frozen sperm from the epididymis can result in successful fertilization. The epididymal sperm retrieved via MESA can be cryopreserved for an in-vitro fertilization (IVF) procedure, thus, making repeat surgical retrieval of sperm unnecessary. We report a retrospective analysis of 24 ICSI cycles in 16 patients with obstructive or nonreconstructable azoospermia. Fresh epididymal sperm was used in 13 ICSI cycles and frozen-thawed epididymal sperm was used in the other 11. We compared the fertilization capability of ICSI using frozen-thawed epididymal sperm with fresh epididymal sperm. Eleven patients became pregnant and five of these pregnancies resulted from frozen epididymal sperm. The fertilization rate per oocyte was 58% with fresh sperm, and 66% with frozen-thawed sperm. The rate of clinical pregnancy for one embryo transfer was 46% with fresh sperm, and 45% with frozen-thawed sperm. There were no significant differences between fresh and frozen-thawed spermatozoa in the fertilization rate of oocytes or the clinical pregnancy rate. Our results suggest that we should cryopreserve supernumerary spermatozoa during a MESA/ICSI procedure in order to avoid repeated scrotal surgery.