Abstract
Purpose: To compare the effects of two different blastocyst thawing protocols on implantation, pregnancy, and live birth rates.
Methods: Ninety four consecutive frozen-thawed blastocyst transfers from 1996 to 2002 were retrospectively analyzed. Blastocysts were cryopreserved using Menezo's two-step slow-freezing protocol. Frozen blastocysts were thawed for transfer according to Menezo's stepwise or two-step protocol. Immediately after thawing, assisted hatching was performed and all embryos were cultured for 3 to 5 h before transfer. Only viable embryos were selected for transfer.
Results: Implantation, pregnancy (determined by the presence of fetal cardiac activity), and live birth rates were significantly higher with two-step (25, 45.7, and 42.9%) than with stepwise thawing protocol (9.2, 18.6, and 16.9%, P<0.01). The percentage of gestational sacs resulting in live babies was higher with two-step thawing (76.6%) than with stepwise thawing (50%, P=0.04).
Conclusions: We conclude that the two-step thawing protocol offers advantages over the stepwise method. The two-step thawing protocol dramatically increased embryo implantation potential, resulting in higher pregnancy rate, and subsequent live birth rate, after frozen blastocyst transfer.
Keywords: Blastocyst, embryo cryopreservation, implantation rate, live birth, pregnancy rate
Full Text
The Full Text of this article is available as a PDF (263.8 KB).
REFERENCES
- 1.Gardner DK, Vella P, Lane M, Wagley L, Schlenker T, Schoolcraft WB. Culture and transfer of human blastocysts increases implantation rates and reduces the need for multiple embryo transfers. Fertil Steril. 1998;69:84–88. doi: 10.1016/S0015-0282(97)00438-X. [DOI] [PubMed] [Google Scholar]
- 2.Gardner DK, Lane M. Culture of viable human blastocysts in defined sequential serum-free media. Hum Reprod. 1998;13(Suppl3):148–159. doi: 10.1093/humrep/13.12.3434. [DOI] [PubMed] [Google Scholar]
- 3.Menezo Y, Nicollet B, Herbaut N, Andre D. Freezing cocultured human blastocysts. Fertil Steril. 1992;58:977–980. doi: 10.1016/s0015-0282(16)55445-4. [DOI] [PubMed] [Google Scholar]
- 4.Menezo Y, Veiga A. In Proceedings of the 10th World Congress on In Vitro Fertilization and Assisted Reproduction. Vancouver: Canada; 1997. Cryopreservation of blastocysts; pp. 49–53. [Google Scholar]
- 5.Behr B, Gebhardt J, Lyon J, Milki AA. Factors relating to a successful cryopreserved blastocyst transfer program. Fertil Steril. 2002;77:697–699. doi: 10.1016/S0015-0282(01)03267-8. [DOI] [PubMed] [Google Scholar]
- 6.Kaufmann RA, Menezo Y, Hazout A, Nicollet B, DuMont M, Servy EJ. Cocultured blastocyst cryopreservation. Fertil Steril. 1995;6:1125–1129. [PubMed] [Google Scholar]
- 7.Nakayama T, Goto Y, Kanzaki H. T., akabatake K, Himeno T, Takakura K, Mori T, Noda Y. Developmental potential of frozen-thawed human blastocysts. J Assist Reprod Genet. 1995;12:239–243. doi: 10.1007/BF02212925. [DOI] [PubMed] [Google Scholar]
- 8.Pantos K, Stefanidis K, Pappas K, Kokkinopoulos P, Petroutsou K, Kokkali G, Stavrou D, Tzigounis V. Cryopreservation of embryos, blastocysts, and pregnancy rates of blastocysts derived from frozen-thawed embryos and frozen-thawed blastocysts. J Assist Reprod Genet. 2001;18:579–582. doi: 10.1023/A:1013138703680. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 9.Alper MM, Brinsden P, Fischer R, Wikland M. To blastocyst or not to blastocyst? That is the question. Hum Reprod. 2001;16:617–619. doi: 10.1093/humrep/16.4.617. [DOI] [PubMed] [Google Scholar]
- 10.Virant-Klun I, Tomazevic T, Bacer-Kermavner L, Mivsek J, Valentincic-Gruden B, Meden-Vrtovec H. Successful freezing and thawing of blastocysts cultured in sequential media using a modified method. Fertil Steril. 2003;79:1428–1433. doi: 10.1016/S0015-0282(03)00395-9. [DOI] [PubMed] [Google Scholar]
- 11.Gardner DK, Lane M, Stevens J, Schoolcraft WB. Changing the start temperature and cooling rate in a slow-freezing protocol increases human blastocyst viability. Fertil Steril. 2003;79:407–410. doi: 10.1016/S0015-0282(02)04576-4. [DOI] [PubMed] [Google Scholar]