Pregnancies achieved after frozen–thawed pronuclear oocytes obtained by intracytoplasmic sperm injection with spermatozoa extracted from frozen–thawed testicular tissues from non-obstructive azoospermic men

Abstract

The use of frozen–thawed testicular tissue as a source of spermatozoa for intracytoplasmic sperm injection (ICSI) in non-obstructive azoospermia yields favourable fertilization and pregnancy rates while avoiding both repetitive biopsies and unexpected cycle cancellations. Spermatozoa were obtained from frozen–thawed testicular biopsy specimens from 67 non-obstructive azoospermic men. Following fertilization, supernumerary two pronuclear (2PN) oocytes were frozen. After thawing, 17 cycles of embryo transfer were carried out with a mean number of 2.7 embryos and a mean cumulative embryo score (CES) of 18.3 per transfer. The clinical pregnancy and implantation rates per transfer in these cycles (23.5 and 8.3% respectively) were comparable to those of fresh embryo transfers (35.7 and 12.7% respectively) with a mean number of 2.7 embryos and a mean CES of 28.7 per transfer. Abortion rates, although higher with cryopreserved 2PN oocytes were not significantly different. With this approach, cryopreservation of supernumerary 2PN oocytes can be used to improve the cumulative pregnancy rates in a severely defective spermatogenetic population. To our knowledge, these are the first pregnancies reported which have been obtained by the transfer of cryopreserved pronuclear oocytes obtained from ICSI using cryopreserved testicular spermatozoa.