Oocytes or embryo storage?

Abstract

Objective: The problem of supernumerary embryos in assisted reproduction techniques (ART)is still unsolved. Embryo cryopreservation often only postpones the problem and, in addition, it is not allowed in all Countries. Oocytes cryopreservation may be an alternative especially now that a certain efficiency of this technique has been demostrated. Insemination of a limited number of oocytes and storage of supernumerary eggs would have an ethical advantage without reducing the cycle efficiency. The aim of this study is to compare the effects of inseminating 4 or more than 4 eggs in terms of fertilization and pregnancy rates and the results of excess oocytes or embryo cryopreservation.Design: Evalutation of the efficiency of inseminating a limited number of oocytes and storing the excess eggs.Materials/Methods: Superovulation was induced with the association of recombinant FSH (Gonal-F) and GnRH agonist (Enantone) and transvaginal oocytes pick-up was performed in 78 patients undergoing ART. In 41 cycles (group 1)no more than 4 oocytes were inseminated and excess eggs were frozen while in 37 cycles (group 2) all the oocytes were insemineted and excess embryos were frozen. ICSI and standard culture procedures were used and embryo transfers were done on day 2.Results: In group 1, 360 eggs were retrieved, 206 were frozen, 124 mature oocytes were inseminated. The fertilization rate was 76%. A mean number of 2.7 ± 1.0 embryos were transferred per cycle. In group 2, 433 oocytes were collected and 346 mature eggs were inseminated with a fertilization rate of 69%. 2.6 ± 1.0 embryos per cycle were transferred and 3.5 ± 0.5 ± per cicle were frozen. Embryo quality was similar in the two groups. Pregnancy rate per transfer was 24.2% and 26.4% in group 1 and group 2 rispectively. Subsequent pregnancy rate in 19 thawing cycles of frozen oocytes were 17.2% and 18.7% in 23 thawing cycles of cryopreserved embryos.Conclusions: Comparison between elective insemination of a limited number oocytes or insemination of all eggs retrieved documented a similar fertilization rate, embryo quality and pregnancy rate. Pregnancy rate from thawed oocytes and thawed embryos are also similar. These data documents that storing excess eggs may be an efficient alternative to embryo cryopreservation with ethical and legal advantages. Objective: The problem of supernumerary embryos in assisted reproduction techniques (ART)is still unsolved. Embryo cryopreservation often only postpones the problem and, in addition, it is not allowed in all Countries. Oocytes cryopreservation may be an alternative especially now that a certain efficiency of this technique has been demostrated. Insemination of a limited number of oocytes and storage of supernumerary eggs would have an ethical advantage without reducing the cycle efficiency. The aim of this study is to compare the effects of inseminating 4 or more than 4 eggs in terms of fertilization and pregnancy rates and the results of excess oocytes or embryo cryopreservation. Design: Evalutation of the efficiency of inseminating a limited number of oocytes and storing the excess eggs. Materials/Methods: Superovulation was induced with the association of recombinant FSH (Gonal-F) and GnRH agonist (Enantone) and transvaginal oocytes pick-up was performed in 78 patients undergoing ART. In 41 cycles (group 1)no more than 4 oocytes were inseminated and excess eggs were frozen while in 37 cycles (group 2) all the oocytes were insemineted and excess embryos were frozen. ICSI and standard culture procedures were used and embryo transfers were done on day 2. Results: In group 1, 360 eggs were retrieved, 206 were frozen, 124 mature oocytes were inseminated. The fertilization rate was 76%. A mean number of 2.7 ± 1.0 embryos were transferred per cycle. In group 2, 433 oocytes were collected and 346 mature eggs were inseminated with a fertilization rate of 69%. 2.6 ± 1.0 embryos per cycle were transferred and 3.5 ± 0.5 ± per cicle were frozen. Embryo quality was similar in the two groups. Pregnancy rate per transfer was 24.2% and 26.4% in group 1 and group 2 rispectively. Subsequent pregnancy rate in 19 thawing cycles of frozen oocytes were 17.2% and 18.7% in 23 thawing cycles of cryopreserved embryos. Conclusions: Comparison between elective insemination of a limited number oocytes or insemination of all eggs retrieved documented a similar fertilization rate, embryo quality and pregnancy rate. Pregnancy rate from thawed oocytes and thawed embryos are also similar. These data documents that storing excess eggs may be an efficient alternative to embryo cryopreservation with ethical and legal advantages.